Drive device

ABSTRACT

The driving device includes a bendable shape memory alloy member, a resilient member for applying a tension to the shape memory alloy member in a longitudinal direction thereof, a bending member for bending the shape memory alloy member, and a movable body moved by a displacement of the shape memory alloy member. The bending member contacts the shape memory alloy member, so that the tension is applied to the shape memory alloy member in the longitudinal direction thereof. Compared with the driving device in which the shape memory alloy member is linearly disposed, the decrease in the amount of displacement can be suppressed, so that a space efficiency can be enhanced and the downsizing of the driving device can be accomplished.

TECHNICAL FIELD

This invention relates to a driving device, and particularly relates toa driving device that utilizes the characteristics of a shape memoryalloy to generate a driving force.

BACKGROUND ART

Conventionally, there is known a driving device using a shape memoryalloy in the form of a wire, as disclosed in, for example, JapaneseLaid-Open Patent Publication Nos. 2000-310181 (see Page 2, FIG. 11) andHEI 5-224136 (see Page 3, FIG. 3). Such a driving device utilizes thecharacteristics of the shape memory alloy member that changes to amemorized shape when the shape memory alloy member is heated to atemperature higher than a transformation temperature, and returns to itsoriginal shape when the shape memory alloy member is cooled to atemperature lower than the transformation temperature. The amount ofdisplacement of the shape memory alloy member is several percents of theentire length of the shape memory alloy member, and therefore it isnecessary to increase the entire length of the shape memory alloy memberin order to obtain the sufficient output (the amount of displacement) ofthe driving device. However, if the shape memory alloy member islinearly disposed, it is necessary to provide a large space.

Therefore, a driving device is recently proposed, in which the shapememory alloy member is wound around a winding member so that the shapememory alloy member whose entire length is long can be disposed in asmall space. Such a driving device is disclosed in, for example,Japanese Laid-Open Patent Publication Nos. 2000-31018 (see Page 6, FIG.1), HEI 8-226376 (see Pages 3-5, FIG. 1), HEI 10-148174 (see Pages 2-3,FIG. 1), and HEI 8-77674 (see Page 5, FIG. 5).

However, if the shape memory alloy member is wound around the windingmember as disclosed in these publications, the amount of displacement ofthe shape memory alloy member decreases, compared with the case in whichthe shape memory alloy member is linearly disposed.

DISCLOSURE OF INVENTION

The present invention is intended to solve the above described problems,and an object of the present invention is to provide a driving devicecapable of suppressing the decrease in the amount of displacementcompared with a driving device in which a shape memory alloy member islinearly disposed, and capable of being disposed in small space (i.e.,capable of enhancing a space efficiency).

A driving device according to the present invention includes a bendableshape memory alloy member, an urging means that applies a tension to theshape memory alloy member in a longitudinal direction thereof, a bendingmeans which bends the shape memory alloy member and has a plurality ofcontact portions contacting the shape memory alloy member, the contactportions being disposed along a closed path, wherein the contact.portions contact the shape memory alloy member so that the tension isapplied to the shape memory alloy member in the longitudinal directionthereof.

According to the present invention, it becomes possible to suppress thedecrease in the amount of displacement of a shape memory alloy member,and capable of enhancing a space efficiency so as to accomplish thedownsizing of the driving device.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view showing a driving device according to Embodiment 1of the present invention;

FIG. 2 is a perspective view showing the driving device according toEmbodiment 1 of the present invention;

FIG. 3 is a perspective view showing a driving device according to acomparative example with respect to Embodiment 1 of the presentinvention;

FIG. 4 is a perspective view showing a driving device according toanother comparative example with respect to Embodiment 1 of the presentinvention;

FIG. 5 is a perspective view for illustrating an experiment regardingthe driving device shown in FIG. 3;

FIG. 6(a) is a perspective view for illustrating an experiment on thedriving device shown in FIG. 4, and FIG. 6(b) is a plan view thereof;

FIG. 7(a) is a perspective view for illustrating an experiment on thedriving device shown in FIG. 4 with a winding pattern of a shape memoryalloy member being varied, and FIG. 7(b) is a plan view thereof;

FIG. 8(a) is a perspective view for illustrating an experiment on thedriving device shown in FIG. 4 with the winding pattern of the shapememory alloy member being varied, and FIG. 8(b) is a plan view thereof;

FIG. 9 is a plan view showing a driving device according to Embodiment 2of the present invention;

FIG. 10 is a perspective view showing a driving device according toEmbodiment 3 of the present invention;

FIG. 11 is a perspective view showing a driving device according toEmbodiment 4 of the present invention;

FIG. 12 is a plan view showing a driving device according to Embodiment5 of the present invention;

FIG. 13 is a plan view showing another configuration example of adriving device according to Embodiment 5 of the present invention;

FIG. 14 is a perspective view showing a driving device according toEmbodiment 6 of the present invention;

FIG. 15(a) is a perspective view for illustrating an experiment on thedriving device according to Embodiment 6 of the present invention, andFIG. 15(b) is a plan view thereof;

FIG. 16(a) is a perspective view for illustrating an experiment on thedriving device according to Embodiment 6 of the present invention, witha winding angle of a shape memory alloy member being varied, and FIG.16(b) is a plan view thereof;

FIG. 17(a) is a perspective view for illustrating an experiment on thedriving device according to Embodiment 6 of the present invention, withthe winding angle of the shape memory alloy member being further varied,and FIG. 17(b) is a plan view thereof;

FIG. 18(a) is a perspective view for illustrating the shape of a bendingmember according to Embodiment 6 of the present invention, and FIGS.18(b), 18(c) and 18(d) are plan views showing concrete shapes of thebending member;

FIG. 19 is a graph showing a relationship between a contact ratio and adisplacement ratio, which corresponds to Table 1;

FIG. 20 is a graph showing the relationship between the contact ratioand the displacement ratio, which corresponds to Table 2;

FIG. 21(a) is a plan view showing the shape of the bending memberaccording to Embodiment 6 of the present invention, and FIGS. 21(b) and21(c) are plan views illustrating other configuration examples of thebending member;

FIG. 22 is a plan view showing a driving device according to Embodiment7 of the present invention;

FIG. 23 is a perspective view showing a driving device according toEmbodiment 8 of the present invention;

FIG. 24(a) is a perspective view showing a driving device according toEmbodiment 9 of the present invention, and FIG. 24(b) is a side viewthereof;

FIG. 25(a) is a perspective view showing a driving device according toEmbodiment 10 of the present invention, and FIG. 25(b) is a perspectiveview seen in the different direction;

FIG. 26 is a perspective view showing a driving device according toEmbodiment 11 of the present invention;

FIG. 27 is a plan view for illustrating an experiment on the drivingdevice according to Embodiment 11 of the present invention;

FIGS. 28(a), 28(b), 28(c) and 28(d) are plan views of winding membersused in the experiment of FIG. 27;

FIG. 29 is a graph showing a result of the experiment on the drivingdevice according to Embodiment 11 of the present invention;

FIG. 30 is a perspective view showing a driving device according toEmbodiment 12 of the present invention;

FIG. 31 is a perspective view for illustrating an experiment on thedriving device according to Embodiment 12 of the present invention;

FIGS. 32(a), (b), (c) and (d) are plan views for respectivelyillustrating experiments using bending members having differentsectional shapes;

FIGS. 33(a), (b), (c) and (d) are plan views respectively showing fourkinds of bending members in the form of approximately triangle column;

FIGS. 34(a), (b), (c) and (d) are plan views respectively showing fourkinds of bending members in the form of approximately square column;

FIGS. 35(a), (b), (c) and (d) are plan views respectively showing fourkinds of bending members in the form of approximately hexagonal column;

FIGS. 36(a), (b), (c) and (d) are plan views respectively showing fourkinds of bending members in the form of approximate cylinder;

FIG. 37 is a graph showing a relationship between the contact ratio andthe displacement ratio, which corresponds to Table 4;

FIGS. 38(a) and (b) are views for illustrating steps of a method forfixing a shape memory alloy member according to Embodiment 13 of thepresent invention to a crimp contact, and FIGS. 38(c) and (d) are viewsfor illustrating another example of the steps;

FIG. 39 is a view for illustrating the following step succeeding to thestep shown in FIG. 38(b) or FIG. 38(d);

FIG. 40 is a perspective view of a driving device according toEmbodiment 14 of the present invention;

FIG. 41(a) is a perspective view showing a driving device according to acomparative example with respect to Embodiment 14 of the presentinvention, and FIG. 41(b) is a perspective view showing a configurationexample of the driving device as another comparative example;

FIG. 42 is a perspective view showing a driving device according toEmbodiment 15 of the present invention;

FIG. 43 is a perspective view showing another configuration example ofthe driving device according to Embodiment 15 of the present invention;

FIG. 44 is a perspective view showing a driving device according toEmbodiment 16 of the present invention;

FIG. 45 is a perspective view showing an experiment on the drivingdevice according to Embodiment 16 of the present invention;

FIG. 46 is a graph showing a result of the experimental shown in FIG.45, which corresponds to Table 5;

FIG. 47 is a perspective view of another configuration example of thedriving device according to Embodiment 16 of the present invention;

FIG. 48 is a perspective view showing the driving device according toEmbodiment 16 of the present invention;

FIG. 49 is a block diagram showing an energizing circuit of the drivingdevice according to Embodiment 16 of the present invention;

FIG. 50 is a block diagram showing an energizing circuit in the casewhere a uniform current flows throughout the shape memory alloy member,which is a comparative example with respect to Embodiment 16 of thepresent invention;

FIG. 51 is a circuit diagram of an energizing circuit shown in FIG. 49;

FIG. 52 is a perspective view showing a driving device according toEmbodiment 17 of the present invention;

FIG. 53 is a perspective view showing another configuration example ofthe driving device according to Embodiment 17 of the present invention;

FIG. 54 is a perspective view showing a driving device according toEmbodiment 18 of the present invention;

FIG. 55 is a perspective view of showing a driving device according toEmbodiment 19 of the present invention;

FIGS. 56(a), (b) and (c) are perspective views respectively showingthree kinds of experimental arrangements for carrying out experiments onthe driving device according to Embodiment 19 of the present invention;

FIG. 57 is a graph showing a result of the experiment using theexperimental arrangements shown in FIG. 56, which corresponds to Table6;

FIG. 58 is a perspective view showing a driving device according toEmbodiment 20 of the present invention;

FIG. 59 is a perspective view showing an experimental arrangement forcarrying out an experiment on the driving device according to Embodiment20 of the present invention;

FIG. 60 is a graph showing a result of the experimental using theexperimental arrangement shown in FIG. 59, which corresponds to Table 7;

FIG. 61(a) is a perspective view showing a driving device according toEmbodiment 21 of the present invention, and FIG. 61(b) is a perspectiveview showing another configuration example of the driving deviceaccording to Embodiment 21 of the present invention;

FIG. 62(a) is a perspective view showing still another configurationexample of the driving device according to Embodiment 21 of the presentinvention, and FIG. 62(b) is a perspective view showing yet anotherconfiguration example of the driving device according to Embodiment 21of the present invention;

FIG. 63(a) is a perspective view showing still another configurationexample of the driving device according to Embodiment 21 of the presentinvention, FIG. 63(b) is a front view thereof, and FIG. 63(c) isperspective view seen in the different direction; and

FIGS. 64(a) and 64(b) are a sectional view and a perspective viewshowing a configuration example in the case where the conventionaldriving device is applied to drive a lens of a camera, which is acomparative example with respect to Embodiment 21.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1.

FIGS. 1 and 2 are a plan view and a perspective view showing a drivingdevice 1 according to Embodiment 1 of the present invention. As shown inFIGS. 1 and 2, a base 6 of the driving device 1 has a placing surface 6a and a wall surface 6 b perpendicular to the placing surface 6 a. Onthe placing surface 6 a, a pin-shaped bending member 5 is planted on aposition distanced from the wall surface 6 b. A shape memory alloymember 2 is wound around the circumferential surface of the bendingmember 5 at a winding angle θ of 180 degrees, with one end (fixed end)being fixed to a wall surface 6 b, with the other end (movable end)being fixed to a side of a movable body 3. The expression that thewinding angle is 180 degrees means that the shape memory alloy member 2contacts the bending member 5 and is bent at 180 degrees. An end of aresilient member 4 made of a tension coil spring is fixed to the wallsurface 6 b, and the other end of the resilient member 4 is fixed to theother side (the side opposite to the side fixed to the shape memoryalloy member 2) of the movable body 3 in such a manner that theresilient member 4 is slightly stretched to cause a predeterminedtension.

In the driving device 1, an energizing circuit 7 causes a direct currentto flow between the fixed end of the shape memory alloy 2 and the fixedend (the end fixed to the wall surface 6 b) of the resilient member 4,so as to heat the shape memory alloy member 2 by means of heat (Jouleheat) caused by the electric resistance of the shape memory alloy member2. For this purpose, a conducting material is used for the resilientmember 4 and the movable body 3. However, the method for heating theshape memory alloy member 2 is not limited to this method. It ispossible that the movable body 3 contacts the placing surface 6 a. Insuch a case, the friction generated between the movable body 3 and theplacing surface 6 a when the movable body 3 moves is negligible comparedto the tension applied to the shape memory alloy member 2.

The bending member 5 constitutes a bending means that bends the shapememory alloy member 2. A portion of the circumferential surface of thebending member 5 contacting the shape memory alloy member 2 constitutesa contact portion of the bending means contacting the shape memory alloymember 2. The base 6 constitutes a holding means that holds the bendingmember 5.

In the above constructed driving device 1, when the energizing circuit 7causes a predetermined direct current (for example, 100 mA) to flowsthrough the shape memory alloy member 2, the shape memory alloy member 2is heated and contracted, so that the movable body 3 moves in thedirection of an arrow A resisting the urging force of the resilientmember 4. When the energization of the shape memory alloy member 2 isstopped, the temperature of the shape memory alloy member 2 decreasesand the shape memory alloy member 2 is expanded to its original length,so that the movable body 3 moves in the direction of an arrow B by theurging force of the resilient member 4.

FIG. 3 is a plan view showing a driving device according to acomparative example with respect to this embodiment, i.e., a drivingdevice 100 in which a shape memory alloy member 101 is linearlydisposed. An end of the shape memory alloy member 101 is fixed to afixed wall 104 a, and the other end is fixed to a side (a right side inFIG. 3) of a movable body 102. The other side (a left side in FIG. 3) ofthe movable body 102 is fixed to an end of a resilient member 103. Theother end of the resilient member 103 is fixed to another fixed wall 104b. Due to the urging force of the resilient member 103, a tension isapplied to the shape memory alloy member 101 in the longitudinaldirection thereof, so that the shape memory alloy member 101 is linearlydisposed without slackening. The heating of the shape memory alloymember 101 is carried out by the energization of an energizing circuit105. When the shape memory alloy member 101 is energized by theenergizing circuit 105, the shape memory alloy member 101 is contracted,so that the movable body 102 moves in a direction shown by an arrow A.When the energization of the shape memory alloy member 101 is stopped,the movable body 102 moves in a direction. shown by an arrow B. However,in the driving device 100, since the shape memory alloy member 101 islinearly disposed, it is difficult to reduce the dimension of the devicein the longitudinal direction of the shape memory alloy member 101.

FIG. 4 is a view showing another comparative example with respect to theembodiment, i.e., a driving device 110 in which a shape memory alloymember 101 is wound around a cylindrical winding member 106 having alarge diameter (for example, a diameter of 10 mm) at about 360 degrees.By winding the shape memory alloy member 101 around the winding member106 at about 360 degrees, the shape memory alloy member 101 whose entirelength is long can be disposed in a small space (i.e., the spaceefficiency can be enhanced). However, the amount of displacement of themovable body 102 becomes smaller compared with the driving device 100shown in FIG. 3.

An experimental result on the driving devices 100 and 110 according tothe comparative examples will be described. FIG. 5 shows an experimentalmethod in the case where a shape memory alloy member 101 is linearlydisposed (corresponding to the driving device 100 of FIG. 3). Crimpcontacts 120 are fixed to both ends of the shape memory alloy member 101in the form of a wire having a diameter of 60 μm and a length of 50 mm.One of the crimp contacts 120 is fixed to a fixing pin 121 a, and theother of the crimp contacts 120 is fixed to an end of a resilient member103. The other end of the resilient member 103 is fixed to anotherfixing pin 121 b. The amount of displacement of the movable body 102(FIG. 3) is evaluated by measuring the amount of displacement of thecrimp contact 120 connecting the shape memory alloy member 101 and theresilient member 103. The resilient member 103 (tension coil spring) isexpanded by 1 mm in a state where the shape memory alloy member 101 isnot energized. A resilient member 103 causes the tension of about49×10⁻³ N when the resilient member 103 is expanded by 1 mm, and causesthe tension of about 98×10⁻³ N when the resilient member 103 is furtherexpanded by 1 mm (i.e., when the shape memory alloy member 2 iscontracted by 1 mm).

Moreover, as shown in FIG. 6(a) and (b), the same experiment is carriedout in such a manner that the shape memory alloy member 101 in the formof a wire is wound around a cylindrical winding member 106 having adiameter of 10 mm at about 180 degrees. The winding member 106 is madeof POM (polyoxymethylene) or ABS (Acrylonitrile-Butadiene-Styreneresin). The length C of the shape memory alloy member 101 from thewinding member 106 to each crimp contact 120 is set to be 17.1 mm.Further, as shown in FIGS. 7(a) and (b), the same experiment is carriedout in such a manner that the shape memory alloy member 101 is woundaround the winding member 106 at 360 degrees. The lengths C1 and C2 ofthe shape memory alloy member 101 from the winding member 106 to therespective crimp contacts 120 are set to be 9.3 mm. Furthermore, asshown in FIGS. 8(a) and (b), the same experiment is carried out in sucha manner that the shape memory alloy member 101 is wound around thewinding member 106 at 450 degrees. The length C of the shape memoryalloy member 101 from the winding member 106 to each crimp contact 120is set to be 11 mm.

As a result of the experiment, when the shape memory alloy member 101 islinearly disposed as shown in FIG. 5, the amount of displacement of theend of the shape memory alloy member 101 is 1.6 mm. In contrast, in theexperiment in which the shape memory alloy member 101 is wound aroundthe winding member 106 having a diameter of 10 mm at about 180 degreesas shown in FIG. 6, the amount of displacement is about 1.0 mm in eachof cases where POM and ABS are used. Moreover, in the experiment inwhich the shape memory alloy member 101 is wound at about 360 degrees asshown in FIG. 7, the amount of displacement is 0.5 mm (when the windingmember 106 is POM) and 1.0 mm (when the winding member 106 is ABS).Moreover, in the experiment in which the shape memory alloy member 101is wound at about 450 degrees as shown in FIG. 8, the amount ofdisplacement is 0.3 mm (when the winding member 106 is POM) and 0.6 mm(when the winding member 106 is ABS). That is, it is understood that theamount of displacement of the shape memory alloy member 101 decreases toabout 35% (POM) and about 61% (ABS) when the winding angle is 360degrees, and decreases to about 20% (POM) and about 36% (ABS) when thewinding angle is 450 degrees, compared with the case in which the shapememory alloy member 101 is linearly disposed (FIG. 5).

Next, the result of the same experiment on the driving device 1according to the embodiment (FIGS. 1 and 2) will be described. Theexperiment is carried out in the same method as that shown in FIG. 5.The bending member 5 is a pin-shaped member made of metal having adiameter of 1 mm. The shape memory alloy member 2 is formed in the formof a wire having a diameter of about 60 μm and the length of 50 mm. Whenthe shape memory alloy member 2 is not energized, the length of theshape memory alloy member 2 from the movable body 3 (the crimp contact)to the pin 5 is 11.8 mm. The resilient member 4 causes the tension ofabout 49×10⁻³ N when the resilient member 4 is expanded by 1 mm, andcauses the tension of about 98×10⁻³ N when the resilient member 4 isfurther expanded by 1 mm (i.e., when the shape memory alloy member 2 iscontracted by 1 mm).

In the experiment using the driving device 1 according to theembodiment, when the direct current of 100 mA flows through the shapememory alloy member 2 so that the shape memory alloy member 2 is heatedand contracted, the amount of displacement of the end of the shapememory alloy member 2 is 1.5 mm. That is, the amount of displacement ofabout 94% is obtained, with respect to the amount (1.6 mm) ofdisplacement when the shape memory alloy member is linearly disposed. Inother words, it is understood that, by bending the shape memory alloymember 2 using the winding member 5(a metal pin having a diameter of 1mm), it is possible to obtain the amount of displacement of about 94%with respect to the case in which the shape memory alloy member 2 islinearly disposed.

As described above, according to the driving device 1 of the embodiment,the shape memory alloy member 2 is bent by the bending member 5 so thatthe tension is applied to the shape memory alloy member 2 in thelongitudinal direction thereof, and therefore the decrease in the amountof displacement of the movable body 3 can be suppressed, and the shapememory alloy member 2 whose entire length is long can be disposed in asmaller space. In other words, the space efficiency can be enhanced.

Embodiment 2.

FIG. 9 is a plan view showing a driving device 11 according toEmbodiment 2 of the present invention. The driving device 11 isdifferent from the driving device 1 of the above described Embodiment 1(FIGS. 1 and 2 ) in that an additional bending member 12 is added forbending the shape memory alloy member 2 at two positions and two wallportions 13 b and 13 c are formed on a base 13. In the driving device11, parts in common with the driving device 1 of Embodiment 1 areassigned the same reference numerals.

In this driving device 11, the wall portions 13 b and 13 c are formed onboth sides of the base 13. In addition to the bending member 5, abending member 12 is planted on the placing surface 13 a of the base 13on the wall portion 13 b side with respect to the bending member 5. Anend (fixed end) of the shape memory alloy member 2 is fixed to the wallportion 13 c. The shape memory alloy member 2 is wound around thebending members 5 and 12 so that each winding angle is about 180degrees. The other end (movable end) of the shape memory alloy member 2is fixed to the movable body 3.

The bending member 5 is disposed on a position so that opposing portions2 a and 2 b of the shape memory alloy member 2 bent around the bendingmember 5 become almost parallel to each other and do not interfere withthe movement of the movable body 3. As an example of dimension, in thedirection in which the opposing portions 2 a and 2 b extend (the movingdirection of the movable body 3), an interval C2 between the movablemember 3 and the bending member 5 is 12.6 mm, an interval C3 between thebending members 5 and 12 is 10 mm, an interval C4 between the bendingmember 12 and the wall portion 13 c is 22.5 mm. An interval C1 betweenthe bending portions 5 and 12 in a direction perpendicular to thedirection in which the opposing part 2 a and 2 b extend is 5 mm.

The bending members 5 and 12 constitute a bending means which bends theshape memory alloy member 2. Portions of the circumferential surfaces ofthe bending members 5 and 12 contacting the shape memory alloy member 2constitute a contact portion of the bending means contacting the shapememory alloy member 2. The base 13 constitutes a holding means whichholds the bending members 5 and 12.

In the above described configuration, the experiment that has beendescribed with reference to FIG. 5 is carried out. In this case, thepin-shaped bending members 5 and 12 each having a diameter of 1 mm areused. The other measurement conditions are the same as those describedwith reference to FIG. 5. When the direct current of 100 mA flowsthrough the shape memory alloy member 2 so that the shape memory alloymember 2 is heated and contracted, the amount of displacement of themovable body 3 is about 1.3 mm.

In other words, the amount of displacement of the movable body 3 becomesabout 81% with respect to the case in which the shape memory alloymember 2 is linearly disposed. It is understood that the decrease in theamount of displacement (which may accompany the enhancement of the spaceefficiency) can be suppressed.

As described above, according to the driving device of this embodiment,since the shape memory alloy member 2 is bent two times by means. of twopin-shaped bending members 5 and 12, it becomes possible to suppress thedecrease in the amount of displacement of the movable body 3, and toenhance the space efficiency. Further, since two bending members 5 and12 are used, it becomes possible to dispose the walls 13 b and 13 ccloser to each other, and therefore the space efficiency can be furtherenhanced.

Embodiment 3.

FIG. 10 is a perspective view showing the driving device 21 according toEmbodiment 3 of the present invention. This driving device 21 isdifferent from the driving device 1 of Embodiment 1 (FIGS. 1 and 2 ) inthat two bending portions are provided and a plurality of portions forbending the shape memory alloy member 22 (guide grooves) are formed onthe respective bending members 23 and 24. In the driving device 21,parts in common with the driving device 1 of Embodiment 1 are assignedthe same reference numerals.

In this driving device 21, two bending members 24 and 23 are planted onthe base 6 in this order from the side closer to the wall portion 6 b.Four guide grooves 23 a are formed on the circumferential surface of thebending member 23 at intervals in the axial direction of the bendingmember 23. Three guide grooves 24 a are formed on the circumferentialsurface of the bending member 24 at intervals in the axial direction ofthe bending member 24. An end (fixed end) of the shape memory alloymember 22 is fixed to the wall portion 6 b, and the other end (movableend) is fixed to the movable body 3. The shape memory alloy member 22 iswound around four guide grooves 23 a of the bending member 23 and threeguide grooves 24 a of the bending member 24 so that each winding angleis about 180 degrees. In other words, two bending member 23 and 24 havecontact portions at seven positions in total, which contact the shapememory alloy member 22 so as to bend the shape memory alloy member 22.In this embodiment, in order to avoid the short circuit of the shapememory alloy member 22, the bending members 23 and 24 are made ofinsulation material or the like.

Two bending members 23 and 24 constitute a bending means which bends theshape memory alloy member 22. Portions of the respective guide grooves23 a and 24 a contacting the shape memory alloy member 22 constitute acontact portion of the bending means contacting the shape memory alloymember 22. The base 6 constitutes a holding means which holds thebending members 23 and 24. The resilient member 4 constitutes an urgingmeans that urges the shape memory alloy member 22.

In the above described configuration, as is the case with Embodiment 1,the movable body 3 can be displaced by causing a predetermined directcurrent (for example, 100 mA) to flow through the shape memory alloymember 22 by means of the energizing circuit 7 so that the shape memoryalloy member 22 is heated and contracted.

As described above, according to the driving device 21 of thisembodiment, it is possible to efficiently dispose the longer shapememory alloy member 22, and therefore it is possible to suppress thedecrease in the amount of displacement of the movable body 3 and tofurther enhance the space efficiency.

Moreover, since the guide grooves 23 a and 24 a are formed on thebending members 23 and 24, the shape memory alloy member 22 can beeasily wound, the deviation of the winding position of the shape memoryalloy member 22 can be prevented, and the short circuit of the shapememory alloy member 22 can be prevented.

Embodiment 4.

FIG. 11 is a perspective view showing a driving device 31 according toEmbodiment 4 of the present invention. This driving device 31 isdifferent from the driving device 1 (FIGS. 1 and 2 ) of Embodiment 1 inthat four pin-shaped bending member 33, 34, 35 and 36 are provided. Inthe driving device 31, parts in common with the driving device 1 ofEmbodiment 1 are assigned the same reference numerals.

In this driving device 31, four pin-shaped. bending members 33 through36 are provided at positions corresponding to four corners of arectangle of the placing surface 6 a of the base 6. An end (fixed end)of the shape memory alloy member 32 is fixed to the wall portion 6 b,and the shape memory alloy member 32 is wound around the bending members33 through 36 in about two turns and half so that each winding angle is90 degrees. The other end (movable end) of the shape memory alloy member32 is fixed to the movable body 3. The shape memory alloy member 32 iswound around the bending members 34 and 35 at three positions axiallyapart from each other, and wound around the bending members 33 and 36 attwo positions axially apart from each other. That is, four bendingmembers 33 through 36 have ten contact portions in total that contactthe shape memory alloy member 32 so as to bend the shape memory alloymember 32. For example, in this embodiment, in order to avoid the shortcircuit of the shape memory alloy member 32, the bending members 33through 36 are made of insulating material. Moreover, it is possible toprovide the guide groove (the guide grooves 23 a and 24 a shown in FIG.10) described in Embodiment 3 on the bending members 33 and 36.

Four bending members 33 through 36 constitute a bending means whichbends the shape memory alloy member 32. Portions of the bending members33 through 36 contacting the shape memory alloy member 32 constitute acontact portion of the bending means. The base 6 constitutes a holdingmeans which holds the bending members 33 through 36.

In the above described configuration, the movable body 3 can bedisplaced by causing a predetermined direct current (for example, 100mA) to flow through the shape memory alloy member 32 using theenergizing circuit 7 so that the shape memory alloy member 32 is heatedand contracted.

Although the bending portions 33 and 36 are disposed on four apexes ofthe rectangle, it is also possible to properly change the number andpositions of the bending members, as long as the contact portionscontacting the shape memory alloy member 32 are formed along a closedpath. Further, in this example, although four bending members 32 havecontact portions at ten positions in total, it is also possible toproperly change this.

As described above, according to the driving device 31 of thisembodiment, it is possible to efficiently dispose the longer shapememory alloy member 32, and therefore it is possible to suppress thedecrease in the amount of displacement of the movable body 3 and tofurther enhance the space efficiency.

Embodiment 5.

FIG. 12 is a plan view showing a driving device 41 according toEmbodiment 5 of the present invention. This driving device 41 isdifferent from the driving device 1 (FIGS. 1 and 2) of Embodiment 1 inthat a shape memory alloy member 42 is wound around projections 44 a and44 b projecting from corners of a housing 44 so that each winding angleis 90 degrees. In the driving device 41, parts in common with thedriving device 1 of Embodiment 1 are assigned the same referencenumerals.

In the driving device 41, a housing 44 in the form of, for example, arectangular parallelepiped is formed on a placing surface 43 a of a base43. The projections 44 a and 44 b are formed on two corners of thehousing 44 on the sides farther from a wall portion 43 b. Theprojections 44 a and 44 b project in directions almost perpendicular toeach other, and have contact surfaces (for example, cylindricalsurfaces) around which the shape memory alloy member 42 is wound. Theshape memory alloy member 42 is wound around each contact surface of theprojections 44 a and 44 b so that the winding angle (corresponding to abending angle) is 90 degrees.

An end (fixed end) of the shape memory alloy member 42 is fixed to thewall portion 43 b of the base 43, and the shape memory alloy member 42is wound around projections 44 a and 44 b so that each winding angle is90 degrees. The other end (movable end) of the shape memory alloy member42 is fixed to the movable body 3.

The projections 44 a and 44 b constitute a bending means which bends theshape memory alloy member 42. Portions of the respective projections 44a and 44 b contacting the shape memory alloy member 42 constitute acontact portion of the bending means that contacts the shape memoryalloy member 42. The base 43 constitutes a holding means which holds thehousing 44 having the projections 44 a and 44 b.

In the above described configuration, the movable body 3 can bedisplaced by causing a predetermined direct current (for example, 100mA) to flow through the shape memory alloy member 42 by means of theenergizing circuit 7 as in Embodiment 1 so that the shape memory alloymember 42 is heated and contracted.

In this embodiment, the projections 44 a and 44 b project from thecorners of the housing 44. However, the projections 44 a and 44 b are isnot limited to this configuration, but can be fixed to proper positions(in terms of designing) on the housing 44. The winding angle of theshape memory alloy member 42 is not limited to 90 degrees.

Moreover, it is possible to form the guide grooves 23 a and 24 a (FIG.10) described in Embodiment 3 on the projections 44 a and 44 b. Further,it is also possible to form a step 44 c on a position where the shapememory alloy member 42 is wound, so that it becomes easy to wind theshape memory alloy member 42.

As described above, according to the driving device 41 of thisembodiment, since the shape memory alloy member 42 is bent two times (at90 degrees for each) by a pair of projections 44 a and 44 b, the longershape memory alloy member 42 can be efficiently disposed. Further, thehousing 44 constituting a part of the driving device 41 can be utilized,and therefore the space efficiency can be further enhanced.

Embodiment 6.

FIG. 14 is a perspective view showing a driving device 51 according toEmbodiment 6 of the present invention. This driving device 51 isdifferent from the driving device 11 (FIG. 9) of Embodiment 2 in that abending member 54 having convex portions on a circumferential surfacethereof is provided. In the driving device 51, parts in common with thedriving device 11 of Embodiment 2 are assigned the same referencenumerals.

As shown in FIG. 14, the bending member 54 is formed on the placingsurface 13 a of the base, and the bending member 54 is approximately inthe form of a cylinder having minute convex portions on thecircumferential surface thereof. The minute convex portions of thebending member 54 constitute contact portions 54 a that contact theshape memory alloy member 2. The contact portions 54 are elongated inthe axial direction of the bending member 54, and a large number of thecontact portions 54 a are disposed in the circumferential direction ofthe bending member 54.

An end (fixed end) of the shape memory alloy member 2 is fixed to thewall portion 13 c, and the shape memory alloy member 2 is wound aroundthe bending member 54 in one turn so that the total of the bendingangles at the respective contact portions 54 a is 360 degrees. The otherend (movable end) of the shape memory alloy member 2 is fixed to oneside of the movable body 3. The other side of the movable body 3 isfixed to an end of the resilient member 4, and the other end of theresilient member 4 is fixed to the wall portion 13 b.

The bending member 54 constitutes a bending means which bends the shapememory alloy member 2. The contact portions 54 a constitute contactportions (convex portions) that contacts the shape memory alloy member 2in the bending means. The base 31 constitutes a holding means whichholds the bending member 54.

In the above described configuration, the movable body 3 can bedisplaced by causing a predetermined direct current (for example, 100mA) to flow through the shape memory alloy member 2 using the energizingcircuit 7 so that the shape memory alloy member 2 is heated andcontracted, as is the case with Embodiment 1.

Next, the experiment on the driving device 51 according to thisembodiment will be described. As is the case with the experiments shownin the above described FIGS. 5 through 8, the crimp contacts 120 and thefixing pins 121 are arranged as shown in FIGS. 15 through 17.

As shown in FIGS. 15(a) and (b), the shape memory alloy member 2 in theform of a wire is wound around the bending member 54 (having the contactportions 54 a) at about 180 degrees, and the bending member 54 is madeof POM or ABS in the form of a cylinder having a diameter of 10 mm.

The crimp contact 120 at an end of the shape memory alloy member 2 isfixed to the fixing pin 121, and the crimp contact 120 at the other endof the shape memory alloy member 2 is fixed to another fixing pin 121via a resilient member 4. The length C of the shape memory alloy member2 from the bending member 54 to the crimp contacts 120 at both ends ofthe shape memory alloy member 2 are set to be 17.1 mm. As shown in FIGS.16(a) and (b), the shape memory alloy member 2 is wound around thebending member 54 at 360 degrees, and the experiments are carried outsimilarly. The lengths C1 and C2 of the shape memory alloy member 2 fromthe bending member 54 to the crimp contacts 120 at both ends are set tobe 9.3 mm. As shown in FIGS. 17(a) and (b), the shape memory alloymember 2 is wound around the bending member 54 at 450 degrees, and theexperiment is carried out similarly. The length C of the shape memoryalloy member 2 from the bending member 54 to the crimp contacts 120 areset to be 11 mm.

FIG. 18(a) is a perspective view showing an outline shape of the bendingmember used in the respective experiments. FIGS. 18(b) through (d) areplan views showing three kinds of shapes used in the respectiveexperiments. The bending member 54 is an approximately cylindricalmember having a diameter D of 10 mm, and has the contact portions 54 aformed on the circumferential surface thereof with a pitch (P) of 1.56mm. Each contact portion 54 a has a circular-arc cross section having aradius of 5 mm. The widths W1 of the contact portion 54 a are,respectively, 1.05 mm (FIG. 18(b)), 0.78 mm (FIG. 18(c)) and 0.52 mm(FIG. 18(d)). Moreover, the widths W2 of the grooves between adjacentcontact portions 54 a are, respectively, 0.52 mm (FIG. 18(b)), 0.78 mm(FIG. 18(c)) and 1.05 mm (FIG. 18(d)).

The other experimental conditions are the same as those of Embodiment 1.The direct current of 100 mA flows through the shape memory alloy member2 so that the shape memory alloy member 2 is heated and contracted, andthe displacement of the movable end is measured. The result of themeasurement is shown in Tables 1 and 2. Table 1 shows the case where thebending member 54 is made of ABS, Table 2 shows the case where thebending member 54 is made of POM. TABLE 1 DISPLACEMENT DISPLACEMENTCONTACT RATIO CONTACT AMOUTN RATIO (%) RATIO (mm) (%) 450 360 180 (%)450 360 170 33 82 86 90 33 1.3 1.3 1.4 50 77 85 82 50 1.2 1.3 1.3 67 7173 81 67 1.1 1.2 1.3 100  36 61 62 100  0.6 1.0 1.0

TABLE 2 DISPLACEMENT DISPLACEMENT CONTACT RATIO CONTACT AMOUTN RATIO (%)RATIO (mm) (%) 450 360 180 (%) 450 360 170 33 86 91 87 33 1.3 1.4 1.4 5065 68 79 50 1.0 1.0 1.2 67 52 55 72 67 0.8 0.8 1.1 100  20 35 62 100 0.3 0.5 1.0

FIG. 19 is a graph showing the experimental result when ABS is used asthe bending member 54, which corresponds to Table 1. FIG. 20 is a graphshowing the experiment result when POM is used as the bending member 54,which corresponds to Table 2. In FIGS. 19 and 20, a vertical axisindicates a displacement ratio H (%), i.e., a ratio of the measureddisplacement of the movable body 3 with respect to the displacement whenthe shape memory alloy member 2 is linearly disposed. A horizontal axisindicates a contact ratio S (%), i.e., a ratio of the width W1 of thecontact portion 54 a with respect to the pitch P (1.56 mm) of thecontact portion 54 a. For example, if the width W1 of the contactportion 54 a is 0.52 mm (FIG. 18(d)), the contact ratio S is 100×0.52mm/1.56 mm=33%. In FIGS. 19 and 20, marks a, b, and c indicate datarespectively when the winding angle of the shape memory alloy member 2around the bending member 54 is 450 degrees, 360 degrees and 180degrees.

According to FIGS. 19 and 20 (Tables 1 and 2), the displacement ratio Hof the movable body 3 becomes close to 100% (i.e., the amount ofdisplacement when the shape memory alloy member 2 is linearly disposed),as the width W1 of the contact portion 54 a becomes small. Moreover, asthe width W1 of the contact portion 54 a becomes small, the differencein amount of displacement caused by the difference in winding angle ormaterial of the bending members 54 (ABS or POM) becomes small. Inparticular, when the width W1 of the contact portion 54 a is ⅓ of thepitch P (the contact ratio S is about 35%), the displacement ratio Hfurther becomes closer to 100%, and the difference in amount ofdisplacement caused by the difference in winding angle or material ofthe bending members (ABS or POM) almost disappears. In the abovedescribed FIGS. 6 through 8, the amount of displacement of the movablebody 3 largely changes according to the difference in material of thewinding member 106 or winding angle of the shape memory alloy member 2.Conversely, in this embodiment, it is possible to suppress the deviationof the amount of displacement caused by the difference in winding angleof the shape memory alloy member 2 or material of the bending members54. Therefore, the space efficiency can be enhanced, the configurationof the driving device can be simplified, and the operation efficiency ofthe manufacturing process can be enhanced.

In this embodiment, although the contact portions 54 a are formed alongthe approximately circular circumference of the contact member 54 asshown in FIG. 21(a), the contact portions 54 a are not limited to thisconfiguration. For example, the contact portions 54 a can be formedalong a closed path (the circumference of the closed figure), such as acircumference of a approximately rounded triangle or oval, as shown inFIGS. 21(b) and (c).

Embodiment 7.

FIG. 22 is a plan view showing a driving device 61 according toEmbodiment 7 of the present invention. This driving device 61 isdifferent from the driving device 1 (FIG. 1) in that a shape memoryalloy member 62 is made in the form of a coil spring. In the drivingdevice 61, parts in common with the driving device 1 of Embodiment 1 areassigned the same reference numerals.

As shown in FIG. 22, the shape memory alloy member 62 is made in theform of a coil spring, and is wound around a pin-shaped bending member63 planted on a placing surface 6 a of a base 6 so that the windingangle is 180 degrees. An end of the shape memory alloy member 62 isfixed to wall portion 6 b, and the other end is fixed to the movablebody 3.

The pin-shaped bending member 63 constitutes a bending means which bendsthe shape memory alloy member 62. A portion of the circumferentialsurface of the bending member 63 contacting the shape-memory alloymember 62 constitutes a contact portion of the bending means contactingthe shape memory alloy member 62. The base 6 constitutes a holding meanswhich holds the bending member 63.

In the above described configuration, the movable body 3 can bedisplaced by causing a predetermined direct current (for example, 100mA) to flow through the shape memory alloy member 62 by means of theenergizing circuit 7 so that the shape memory alloy member 62 is heatedand contracted. Since the shape memory alloy member 62 takes the form ofa coil spring, the amount of expansion and contraction of the shapememory alloy member 62 becomes large, with the result that the amount ofdisplacement of the movable body 3 can be largely increased.

In this embodiment, although the bending member 63 is pin-shaped, thebending member 63 is not limited to the pin shape, but it is possible tochose the shape of the bending member 63 suitable for the shape memoryalloy member 62 (in the form of the coil-spring) in terms of designing.

As described above, according to the driving device 61 of thisembodiment, since the shape memory alloy member 62 is made in the formof the coil spring, the amount of expansion and contraction of the shapememory alloy member 62 becomes larger, and therefore the amount ofdisplacement of the movable body 3 can be largely increased. Therefore,the space efficiency can be further enhanced, and the downsizing of thedriving device 61 can be accomplished.

Embodiment 8.

FIG. 23 is a perspective view showing a driving device 71 according toEmbodiment 8 of the present invention. This driving device 71 isdifferent from the driving device 1 of Embodiment 1 (FIGS. 1 and 2) inthat a shape memory alloy member 72 in the form of a band is used. Inthe driving device 71, parts in common with the driving device 1 ofEmbodiment 1 are assigned the same reference numerals.

In the driving device 71, the shape memory alloy member 72 is not in theform of a wire but in the form of a band. The shape memory alloy member72 is wound around a pin-shaped bending member 5 planted on a base 6 sothat the winding angle is 180 degrees. An end of the shape memory alloymember 72 is fixed to a wall portion 6 b, and the other end is fixed toa movable body 3.

The pin-shaped bending member 5 constitutes the bending means whichbends the shape memory alloy member 72. A part of the circumferentialsurface of the bending member 5 contacting the shape memory alloy member72 constitutes a contact portion of the bending means contacting theshape memory alloy member 72. The base 6 constitutes a holding meanswhich holds the bending member 5.

In the above described configuration, the movable body 3 can bedisplaced by causing a predetermined direct current (for example, 100mA) to flow through the shape-memory alloy member 72 by means of theenergizing circuit 7 so that the shape memory alloy member 72 is heatedand contracted.

In this embodiment, although the bending member. 5 is pin-shaped, thebending member 5 is not limited to the pin shape. It is possible tochose the shape of the bending member 5 suitable for the shape memoryalloy member 72 (in the form of the band) in terms of designing.

As described above, according to the driving device 71 of thisembodiment, in addition to the advantage of Embodiment 1 that enhancesthe space efficiency, it becomes possible to generate a large forcebecause the shape memory alloy 72 is in the form of a band. Therefore,it becomes possible to move the movable body 3 with a large force.

Embodiment 9.

FIGS. 24(a) and (b) are a front view and a side view showing a drivingdevice 81 according to Embodiment 9 of the present invention. As shownin FIGS. 24(a) and (b), a base 83 has a pair of fixing walls 83 a and 83b opposing to each other. Both ends of the shape memory alloy member 2are fixed to one fixing wall 83 a. The center part of the shape memoryalloy member 2 is wound around a bending member 84 in a plurality ofturns (2.5 turns) so that the winding angle is about 900 degrees. Thebending member 84 is approximately in the form of a cylinder. Thisbending member 84 is composed by adding a rotation axis 84 a to theabove described bending member 54 (FIG. 14) having a plurality ofcontact portions 54 a. Both ends of the rotation axis 84 a are rotatablysupported by a holding frame 85. A resilient member 4 is stretchedbetween the center of a connecting portion 85 a of the holding frame 85and the fixing wall 83 b of the base 83, so that the shape memory alloymember 2 is kept in a state where the shape memory alloy member 2 is notslackened. By the above described configuration, the shape memory alloymember 2 is not slackened, and the position of the bending member 84 isstably determined.

The bending member 84 constitutes a bending means which bends the shapememory. alloy member 2. A part of the circumferential surface of thebending member 84 contacting the shape memory alloy member 2 constitutesa contact portion of the bending means that contacts the shape memoryalloy member 2. The base 83 constitutes a holding means which holds thebending member 84.

In the above described configuration, when the energizing circuit 7causes a current to flow through the shape memory alloy member 2, theshape memory alloy member 2 is heated and contracted, so that thebending member 84 (and the holding frame 85) is displaced in thedirection of an arrow C resisting the force of the resilient member 4.When the energization of the shape memory alloy member 2 is stopped, theshape memory alloy member 2 is expanded to its original length, and thebending member 84(and the holding frame 85) is displaced in thedirection of an arrow D due to the force of the resilient member 4.Here, although the direction of the movement of a movable body (thebending member 83 and the holding frame 85) shown by arrows C and D isaligned with the direction of the gravity, the direction is notnecessarily aligned with the direction of the gravity, as long as themovable body 3 is able to smoothly move in the direction indicated bythe arrows C and D. Further, in this embodiment, the bending member 84uses an approximately cylindrical member having contact portions 54 a ona circumferential surface thereof. However, as was described withreference to FIG. 21 (Embodiment 6), it is possible to freely design theshape of the bending member 84 such as oval shape, rounded triangle orthe like, according to the conditions of the driving device 81.

As described above, according to the driving device 81 of thisembodiment, it is possible to suppress the decrease in the amount ofdisplacement of the movable body (bending member 84 and holding frame85). Further, by using the shape memory alloy member 2 whose entirelength is long, it is possible to obtain a large driving force and toaccomplish the downsizing of the driving device 81.

Embodiment 10.

FIGS. 25(a) and (b) are perspective views showing a driving device 91according to Embodiment 10 of the present invention, as seen fromdifferent directions. This driving device 91 is different from thedriving device 41 of the Embodiment 5 in that a pin 93 is furtherprovided on a housing 44 for further bending a shape memory alloy member92, in addition to the projections 44 a and 44 b. In the driving device91, parts in common with the driving device 41 of Embodiment 5 areassigned the same reference numerals.

As shown in FIG. 25(a), the housing 44 is provided on, for example, aplacing surface 43 a of a base 43. The projections 44 a and 44 bdescribed in Embodiment 5 are formed on the corners of this housing 44.In addition, the pin 93 (protrusion) is planted on the side surface ofthe housing 44 as shown in FIG. 25(b).

An end (fixed end) of the shape memory alloy member 92 is fixed to awall portion 43 b of the base 43. The shape memory alloy member 92 iswound around the projections 44 a and 44 b so that each winding angle is90 degrees, then bent by the pin 93 at 180 degrees, and again woundaround the projections 44 a and 44 b so that each winding angle is 90degrees. The other end (movable end) of the shape memory alloy 92 isfixed to the movable body 3.

The housing 44 with the projections 44 a and 44 b constitutes a bendingmeans which bends the shape memory alloy member 92. Portions of thecircumferential surfaces of the projections 44 a and 44 b contacting theshape memory alloy member 92 constitutes a contact portion of thebending means that contacts the shape memory alloy member 92. The base43 constitutes a holding means which holds the housing 44 with theprojections 44 a and 44 b.

In the above described configuration, the movable body 3 can bedisplaced by causing a current to flow through the shape memory alloymember 92 by means of the energizing circuit 7 so that the shape memoryalloy member 92 is heated and contracted.

The driving device 91 according to this embodiment has the pin 93 andthe protruding portions 44 a and 44 b, so that the shape memory alloymember 92 is wound around a pair of projections 44 a and 44 b and thepin 93 in five turns (90 degrees and 180 degrees). Therefore, the shapememory alloy member 92 whose entire length is long can be disposed in asmall space. Additionally, since a part of the housing 44 constitutingthe driving device 91 can be utilized, the downsizing of the drivingdevice can be accomplished, while the decrease in the amount ofdisplacement of the movable body 3 can be suppressed and the spaceefficiency can be enhanced.

Embodiment 11.

FIG. 26 is a perspective view showing a driving device 151 according toEmbodiment 11 of the present invention. This driving device 151 isdifferent from the driving device 41 (FIGS. 12 and 13) of Embodiment 5in that minute convex portions 153 are formed on the circumferentialsurfaces of projections 152 a and 152 b of a housing 152. In the drivingdevice 151, parts in common with the driving device 41 of Embodiment 5are assigned the same reference numerals.

In the driving device 41, the housing 152 is provided on, for example, aplacing surface 43 a of a base 43. The projections 152 a and 152 b areformed on corners of the housing 152 and project in directionsperpendicular to each other. Minute convex portions 153 are formed onthe circumferences of the projections 152 a and 152 b, and elongated inthe vertical direction. An end (movable end) of the shape memory alloymember 42 is fixed to the wall portion 43 b of the base 43, and theshape-memory alloy member 42 is wound around the projections 152 b and152 a (in contact with the convex portions 153) so that each windingangle is 90 degrees. The other end (fixed end) of the shape memory alloymember 42 is fixed to a movable body 3.

The housing 152 with the projections 152 a and 152 b constitutes abending means which bends the shape memory alloy member 42. Convexportions 153 of the projections 152 a and 152 b constitute a contactportion of the bending means that contacts the shape memory alloy member42. The base 43 constitutes a holding means which holds the housing 152.

In the above described configuration, the movable body 3 can bedisplaced by causing the direct current to flow through the shape memoryalloy member 42 by means of the energizing circuit 7 so that the shapememory alloy member 42 is heated and contracted.

When the shape memory alloy member 42 is to be bent, it is necessary toprevent the stress concentration caused by the rapid change of thestress, and to prevent a bent habit to thereby enhance a reliability.For this purpose, the diameters of the projections 152 a and 152 b (inthe case where the projections 152 a and 152 b have circular-arc crosssections) are preferably from 20 to 40 times the diameter of the shapememory alloy member 42. However, in such a case, a contact length withwhich the shape memory alloy member 42 contacts the projections 152 aand 152 b increases, and therefore there is a possibility that theamount of displacement may decrease compared with the case in which theshape memory alloy member 42 is linearly disposed.

However, in this embodiment, the convex portions 153 are formed on theprojections 152 a and 152 b in the direction perpendicular to thewinding direction of the shape memory alloy member 42, so that thecontact length between the shape memory alloy member 42 and theprojections 152 a and 152 b (the convex portions 153) is short.Therefore, even when the diameters of the projections 152 a and 152 bare set to be large, it is possible to prevent the decrease in theamount of displacement of the shape memory alloy member 42.

FIG. 27 is a plan view showing an experimental method for verifying theeffect by the provision of the convex portions 153. As shown in FIG. 27,in this experiment, the shape memory alloy member 2 with the crimpcontacts 120 fixed to both ends thereof is wound around a bending member155 a at 360 degrees. The crimp contact 120 at an end (movable end) isfixed to a resilient member 4, and the crimp contact 120 at the otherend (fixed end) is fixed to the fixing pin 121 (FIG. 7(a)). The otherend of the resilient member 4 is fixed to another fixing pin 121 (FIG.7(a)). The energizing circuit 105(FIG. 7(a)) causes a current to flowbetween two fixing pins 121. The shape memory alloy member 2 has alength of 50 mm, and a diameter of 60 μm. The length C of the shapememory alloy member 2 from the bending member 155 a to the fixing pin121 on the fixed end is set to be about 8 mm. Moreover, the tension ofabout 392×10⁻³ N is applied to the shape memory alloy member 2 on anormal condition (when the shape memory alloy member 2 is not energized). Under such a condition, when the direct current of 140 mA flowsthrough the shape memory alloy member 2, the amount of displacement (forexample, the amount of displacement of the crimp contact 120 connectedto the resilient member 4) of the movable end of the shape memory alloymember 2 is measured.

The bending member 155 a is a rectangular column having a square crosssection with projections 156 formed on the four corners, and eachprojection 156 has a circular-arc cross section. The projections 156correspond to the projections 152 a and 152 b of the driving device 151(FIG. 26) of Embodiment 11. By measuring the amount of displacement whenthe shapes of the projections 156 is varied, it is possible to determinethe tendency of the change in the amount of displacement when therespective shapes are adopted to the projections 152 a and 152 b (FIG.26).

FIGS. 28(a) and (d) show plan views showing the respective shapes of thebending members 155 a through 155 d used in this experiment. The bendingmember 155 a through 155 d are made of POM.

The bending member 155 a shown in FIG. 28(a) is a rectangular columnhaving an approximately square cross section, and the projections 156(having a radius R of 3.3 mm) are formed on four corners of therectangular column. Concaves having a depth t of 0.2 mm are formedbetween the projections 156. The ratio of the length of four projections156 contacting the shape memory alloy member 2 with respect to theentire circumferential length of the bending member 155 a, i.e., thecontact ratio is 66%. Each projection 156 is in the form of sector whosecentral angle θ is 90 degrees. In the experiment using this bendingmember 155 a, the amount of displacement of the movable end of the shapememory alloy member 2 is 1.16 mm, and the ratio (i.e., the displacementratio) thereof to the amount of displacement on the same condition inthe case where the shape memory alloy member 2 is linearly disposed (2.1mm) is 55.2%.

The bending member 155 b shown in FIG. 28(b) is a rectangular columnwith an approximately square cross section, and the projections 156(having a radius R of 1.6 mm) are formed on four corners of therectangular column. Concaves having a depth t of 0.2 mm are formedbetween the projections 156. The ratio of the length of four projections156 contacting the shape memory alloy member 2 with respect to theentire circumferential length of the bending member 155 b (the contactratio) is 33%. In the experiment using this bending member 155 b, theamount of displacement of the movable end of the shape memory alloymember 2 is 1.48 mm, and the displacement ratio thereof to the amount ofdisplacement in the case where. the shape memory alloy member 2 islinearly disposed (2.1 mm) is 70.5%.

The bending member 155 c shown in FIG. 28(c) is made by forming twoconcaves having a depth t of 0.2 mm (so as to form three convex portions156 a) on each projection 156 of the bending member 155 a shown in FIG.28(a) . The ratio of the length of the convex portions 156 a of fourprojections 156 contacting the shape memory alloy member 2 with respectto the entire circumferential length of the bending member 155 c (thecontact ratio) is 33%. In the experiment using this bending member 155c, the amount of displacement of the movable end of the shape memoryalloy member 2 is 1.38 mm, and the displacement ratio thereof to theamount of displacement in the case where the shape memory alloy member 2is linearly disposed (2.1 mm) is 65.7%.

The bending member 155 d shown in FIG. 28(d) is made by forming fourconcaves having a depth t of 0.2 mm (so as to form five convex portions156 b) on each projection 156 of the bending member 155 a shown in FIG.28(a). The ratio of the length of the convex portions 156 b of fourprojections 156 contacting the shape memory alloy member 2 with respectto the entire circumferential length of the bending member 155 c (thecontact ratio) is 33%. In the experiment using this bending member 155d, the amount of displacement of the movable end of the shape memoryalloy member 2 is 1.42 mm, and the displacement ratio thereof to theamount of displacement in the case where the shape memory alloy member 2is linearly disposed (2.1 mm) is 67.6%.

The result of the above described experiment is shown in Table 3 andFIG. 29. In FIG. 29, the vertical axis indicates the displacement ratioH (%). Marks a, b, c, and d of a horizontal axis respectively indicatethe experiment results when the bending members 155 a, 155 b, 155 c, and155 d (FIG. 28(a) through (d)) are used. TABLE 3 CONTACT RATIO 66 3333   33   (%) (3 CONVEX (5 CONVEX PORTIONS) PORTIONS) DISPLACEMENT 55.270.5 65.7 67.6 RATIO (%)

As seen from the experimental result shown in Table 3 and FIG. 29, it isunderstood that the amount of displacement of the movable body (themovable end of the shape memory alloy member 2) increases, as thecontact. ratio of the shape memory alloy member decreases. Therefore, indriving device 151 (FIG. 26), it is understood that the amount ofdisplacement of the movable body 3 can be increased by forming theconvex portions 153 on the projections 152 a and 152 b so as to reducethe ratio of the contact portion contacting the shape memory alloymember 42 to the entire circumferential length.

As described above, according to the driving device 151 of thisembodiment, since the minute convex portions 153 are formed on theprojections 152 a and 152 b contacting the shape memory alloy member 42,the amount of displacement of the movable end of the shape memory alloymember 42 can be increased, and the stress concentration on the shapememory alloy member 42 can be prevented, so that the bent habit can beprevented.

Embodiment 12.

FIG. 30 is a perspective view showing the driving device 161 accordingto Embodiment 12 of the present invention. The driving device 161 isdifferent from the driving device 51 (FIG. 14) according to Embodiment 6of the present invention in that a bending member 162 having projections162 b is in the form of a multangular column. In the driving device 161,parts in common with the driving device 51 of Embodiment 6 are assignedthe same reference numerals.

As shown in FIG. 30, the bending member 2 is planted on a placingsurface 13 a of a base 13, and has a plurality of projections 162 b(contact portion) on the circumferential surface thereof. An end (fixedend) of the shape memory alloy member 2 is fixed to a wall portion 13 c,and the shape memory alloy member 2 is wound around the circumferentialsurface of the bending portion 162 so that the total of bending anglesat the respective projections 162 b is 360 degrees. The other end(movable end) of the shape memory alloy member 2 is fixed to a movablebody 3.

The bending member 162 constitutes a bending means which bends the shapememory alloy member 2. Portions of the circumferential surface of thebending member 162 contacting the shape memory alloy member 2constitutes a contact portion of the bending means contacting the shapememory alloy member 2. The base 13 constitutes a holding means whichholds the bending member 162.

In the above described configuration, the movable body 3 can bedisplaced by causing a current to flow through the shape memory alloymember 2 by means of the energizing circuit 7 so that the shape memoryalloy member 2 is heated and contracted.

In the above described Embodiment 6 (FIGS. 14 through 20), it has beendescribed that the decrease in the amount of displacement of the shapememory alloy member 2 can be suppressed by reducing the contact ratio ofthe shape memory alloy member 2 contacting the bending member 54.However, if the bending member 54 is made of resin, as a contact widthof the projection 54 a (a length with which the projection 54 a contactsthe shape memory alloy member 2) decreases, there is a possibility thatthe bending member 54 may be molten by the heat of the shape memoryalloy member 2. Therefore, it is preferable to increase the contactwidth of each projection 54 a and to reduce the contact ratio, if aresin or other material which does not have high heat resistanceproperty is used as the bending member 54. In this respect, theexperiment using the bending members of various sectional shapes will bedescribed.

FIG. 31 is a perspective view of a main part of an experimentalarrangement. As shown in FIG. 31, in this experiment, a crimp contact120 is fixed to an end (fixed end) of the shape memory alloy member 2,and the crimp contact 120 is also fixed to a fixing pin 121. Anothercrimp contact 120 is fixed to another end (movable end) of the shapememory alloy member 2, and the crimp contact 120 is fixed to anotherfixing pin 121 via a resilient member 4. The shape memory alloy member 2has a length of 50 mm and a diameter of 60 μm. The tension applied tothe shape memory alloy member 2 is about 392×10⁻³ N when the shapememory alloy member 2 is not energized.

When a direct current of 140 mA flows through the shape memory alloymember 2, the amount of displacement of the movable end (for example,the amount of displacement of the crimp contact 120 fixed to theresilient member 4) of the shape memory alloy member 2 is measured.

FIG. 32(a) through (d) are plan views for illustrating the experimentsusing four kinds of bending members 162 through 165. In the experimentshown in FIG. 32(a), the bending member 162 in the form of a columnhaving an approximately triangular cross section is used. In theexperiment shown in FIG. 32(b), the bending member 163 in the form of acolumn having an approximately rectangle cross section is used. In theexperiment shown in FIG. 32(c), the bending member 164 in the form of acolumn having an approximately hexagonal cross section is used. In theexperiment shown in FIG. 32(d), the bending member 165 in the form of acylinder having an approximately circular cross section is used. Thebending members 162 through 165 are made of POM. In each case, thedistance C from the bending portion 162 through 165 to the fixed end ofthe shape memory alloy member 2 is 8 mm.

FIGS. 33 through 36 are plan views showing the concrete sectional shapesof the bending members 162 through 165.

The bending member 162 shown in FIG. 33(a) is a triangular column withprojections 162 a having a radius R of 0.5 mm formed on the respectivecorners thereof, and the contact ratio is 10%. The interval S betweenthe adjacent projections 162 a is 9.4 mm. The bending member 162 shownin FIG. 33(b) is a triangular column with projections 162 b having aradius R of 1.6 mm formed on the respective corners thereof, and thecontact ratio is 33%. The interval S between the adjacent projections162 b is 9.4 mm. The bending member 162 shown in FIG. 33(c) is atriangular column with projections 162 c having a radius R of 2.5 mmformed on the respective corners thereof, and the contact ratio is 50%.The interval S between the adjacent projections 162 c is 5.2 mm. Thebending member 162 shown in FIG. 33(d) is a triangular column withprojections 162 d having a radius R of 3.3 mm formed on the respectivecorners thereof, and the contact ratio is 66%. The interval S betweenthe adjacent projections 162 d is 3.6 mm. The above described FIGS. 29and 30 show the cases in which the bending members shown in FIGS. 33(a)through (d) are used.

Similarly, the bending member 163 shown in FIG. 34(a) is a rectangularcolumn with projections 163 a having a radius R of 0.5 mm formed on therespective corners thereof, and the contact ratio is 10%. The interval Sbetween the adjacent projections 163 a is 7.1 mm. The bending member 163shown in FIG. 34(b) is a rectangular column with projections 163 bhaving a radius R of 1.6 mm formed on the respective corners thereof,and the contact ratio is 33%. The interval S between the adjacentprojections 163 b is 5.3 mm. The bending member 163 shown in FIG. 34(c)is a rectangular column with projections 163 c ehaving a radius R of 2.5mm formed on the respective corners thereof, and the contact ratio is50%. The interval S between the adjacent projections 163 c is 3.9 mm.The bending member 163 shown in FIG. 34(d) is a rectangular column withprojections 163 d having a radius R of 3.3 mm formed on the respectivecorners thereof, and the contact ratio is 66%. The interval S betweenthe adjacent projections 163 d is 2.7 mm.

Similarly, the bending member 164 shown in FIG. 35(a) is a hexagonalcolumn with projections 164 a having a radius R of 0.5 mm formed on therespective corners thereof, and the contact ratio is 10%. The interval Sbetween the adjacent projections 164 a is 4.7 mm. The bending member 164shown in FIG. 35(b) is a hexagonal column with projections 164 b havinga radius R of 1.6 mm formed on the respective corners thereof, and thecontact ratio is 33%. The interval S between the adjacent projections164 b is 3.6 mm. The bending member 164 shown in FIG. 35(c) is ahexagonal column with projections 164 c having a radius R of 2.6 mmformed on the respective corners thereof, and the contact ratio is 50%.The interval S between the adjacent projections 164 c is 2.6 mm. Thebending member 164 shown in FIG. 35(d) is a hexagonal column withprojections 164 d having a radius R of 3.3 mm formed on the respectivecorners thereof, and the contact ratio is 66%. The interval S betweenthe adjacent projections 164 d is 1.8 mm.

The bending member 165 shown in FIG. 36(a) is a cylinder having adiameter D of 10 mm, and the contact ratio is 100%. The bending member165 shown in FIG. 35(b) is a cylinder having a diameter D of 10 mm onwhich 20 projections 165 b having a width W1 of 0.52 mm are formed at apitch of 1.56 mm, and the contact ratio is 33%. The width W2 of thegroove between the adjacent projections 165 b is 1.05 mm. The bendingmember 165 shown in FIG. 35(c) is a cylinder having a diameter D of 10mm on which 20 projections 165 c having a width W1 of 0.78 mm are formedat a pitch of 1.56 mm, and the contact ratio is 50%. The width W2 of thegroove between the adjacent projections 165 c is 0.78 mm. The bendingmember 165 shown in FIG. 35(d) is a cylinder having a diameter D of 10mm on which 20 projections 165 d having a width W1 of 1.05 mm are formedat a pitch of 1.56 mm, and the contact ratio is 66%. The width W2 of thegroove between the adjacent projections 165 d is 0.52 mm.

Using these bending members 162 through 165, the displacement of themovable end of the shape memory alloy member 2 is measured as shown inFIGS. 32(a) through (d). The result is shown in Table 4 and FIG. 37. InFIG. 37, the vertical axis indicates the displacement ratio H, and thehorizontal axis indicates the contact ratio S (%). Moreover, in FIG. 37,marks a, b, c and d respectively indicate the results of the experimentsshown in FIGS. 32(a), (b), (c) and (d). TABLE 4 DISPLACEMENT RATIO (%)CONTACT TRI- REC- HEX- RATIO ANGULAR TANGULAR AGONAL (%) COLUMN COLUMNCOLUMN CYLINDER 10 84.2 85.7 80.5 — 33 72.1 70.5 68.1 73.7 50 61.9 60.760.9 58.6 67 52.2 55.2 51 48 100 — — — 37.6

Based on Table 4 and FIG. 37, it is understood that the amount ofdisplacement of the shape memory alloy member 2 does not depend on theshape of the bending members 162 through 165(triangular column,rectangular column or the like), but depends on the contact ratio S.Further, it is understood that the amount of displacement becomeslarger, as the contact ratio S becomes smaller. Therefore, it isunderstood that it is preferable to chose the bending member 162 (FIG.33) having a triangular cross section with small number of sides, inorder to increase the amount of displacement of the shape memory alloymember 2 and to increase the width of the contact portion (forpreventing the melting due to the heat of the shape memory alloy member2).

As described above, according to the driving device 161 (FIG. 30) ofthis embodiment, since the bending member is approximately in the formof a multangular column, it is possible to suppress the decrease in theamount of displacement of the movable body 3 and to chose the width ofthe contact portion so as to prevent the melting. Thus, the melting ofthe projection of the bending member can be prevented, while thedecrease in the amount of displacement of the movable body 3 can besuppressed and the space efficiency can be enhanced. That is, thedownsizing of the driving device can be accomplished.

Embodiment 13.

FIG. 38 and 39 are views for illustrating a fixing method (a crimpingmethod) of a shape memory alloy member 202 and a crimp contact 208. Thecrimp contact 208 is used for fixing an end of the shape memory alloymember 202 to a resilient member (for example, the resilient member 4shown in FIG. 1), a fixing pin or the like.

As shown in FIG. 38(a), the crimp contact 208 is composed of aplate-like member made of metal. The crimp contact 208 has a baseportion 208 bapproximately in the form of oblong, a ring portion 208 cformed on an end in the longitudinal direction of the base portion 208b, and crimp portions 208 a formed on both sides in the width directionof the base portion 208 b. An end of the shape memory alloy member 202is placed on almost the center of the base portion 208 b of the crimpcontact 208, and then the crimp portions 208 a are bent as shown in FIG.38(b), so that the shape memory alloy member 202 and the crimp contact208 are fixed (crimped) to each other. Moreover, as shown in FIG. 38(c),it is also possible to wind the shape memory alloy member 202 around oneof the crimp portions 208 a, and then bend the crimp portion 208 a asshown in FIG. 38(d).

In this embodiment, as shown in FIG. 39, the energizing circuit 207causes a current to flow between the crimp contact 208 and the shapememory alloy member 202. The energizing circuit 207 is connected to anarbitrary position on the crimp contact 208 (including a part 202 b ofthe shape memory alloy member 202 fixed to the crimp contact 208) and toa position 202 a on the shape memory alloy member 202 close to the crimpcontact 208. The energizing circuit 207 causes the current (excesscurrent) to flow through the shape memory alloy member 202, and thecurrent is sufficient for heating the shape memory alloy member 202 to atemperature at which the shape memory alloy member 202 loses the memoryof the shape. Therefore, on the crimp contact 208 side of the shapememory alloy member 202 with respect to the above described position 202a, the memory of the shape is lost.

The effect of this embodiment is as follows. If the shape memory alloymember 202 is simply fixed to the crimp contact 208, the reliability ofthe fixed part of the shape memory alloy member 202 and the crimpportion 208 a may decreases when the shape memory alloy member 202 isrepeatedly expanded and contracted due to the heating and cooling causedby the energizing (or the change in an environmental temperature). Insuch a case, there is a possibility that the shape memory alloy member202 may be dropped out of the crimp portion 208 a or may be cut. In thisembodiment, the part 202 b of the shape memory alloy member 202 fixed tothe crimp contact 208 loses its memory of shape so that the part 202 bis not expanded or contracted, utilizing the characteristics that theshape memory alloy member 202 loses its memory of shape when the shapememory alloy member 202 is heated to a predetermined temperature orhigher. As a result, it is possible to enhance the reliability of theconnection of the shape memory alloy member 202 and the crimp portion208 a, and to prevent that the shape memory alloy member 202 from beingdropped out of the crimp contact 208 or being cut.

Embodiment 14.

FIG. 40 is a perspective view showing a driving device 211 according toEmbodiment 14 of the present invention. The driving device 211 shown inFIG. 40 has pin-shaped bending members 215 a, 215 b, 215 c and 215 dplanted on a base 216 so that the bending members 215 a, 215 b, 215 cand 215 d are disposed on four apexes of quadrangle. On the base 216,fixing pins 219 a and 219 b are planted in this order from the sidecloser to the bending member 215 a. A shape memory alloy member 212 inthe form of a wire is wound around the bending members 215 a, 215 b, 215c and 215 d. A crimp contact 218 a is fixed to an end (fixed end) of theshape memory alloy member 212, and the crimp contact 218 a is fixed tothe fixing pin 219 a. A crimp contact 218 b is fixed to the other end(free end) of the shape memory alloy member 212, and the crimp contact218 b is fixed to an end of a resilient member 214. The other end of theresilient member 214 is fixed to the fixing pin 219 b. Among the bendingmembers 215 a through 215 d, the energizing circuit 217 is connected tothe bending member 215 a which is the closest from the fixed end (thecrimp contact 218 a) of the shape memory alloy member 212 and to thebending member 215 d which is the closest from the movable end (thecrimp contact 218 b). Other configuration is the same as Embodiment 1.

Here, the bending members 215 a through 215 d constitute a bending meanswhich bends the shape memory alloy member 212. Portions of thecircumferential surfaces of the bending members 215 a through 215 dcontacting the shape memory alloy member 212 constitute a contactportion of the bending means contacting the shape memory alloy member212. The base 216 constitutes a holding means which holds the bendingmembers 215 a through 215 d.

In the above described configuration, the movable body (the crimpcontact 218 b) can be displaced by causing the current to flow throughthe shape memory alloy member 212 via the bending members 215 a and 215b by means of the energizing circuit 217, so that the shape memory alloymember 212 is heated and contracted. The current flows through a part ofthe shape memory alloy member 212 between the bending member 215 a andthe bending member 215 d, and does not flow through the crimp contacts218 a and 218 b at both ends of the shape memory alloy member 212.Therefore, parts of the shape memory alloy member 212 fixed to crimpportions 218 c of the crimp contacts 218 a and 218 b are not expanded orcontracted. As a result, the connection between the crimp contacts 218 aand 218 b and the shape memory alloy member 212 is enhanced.

In order to verify the effect of this embodiment, a comparative exampleshown in FIG. 41(a) will be described. In a driving device 211 a, ashape memory alloy member 212 is linearly disposed, and crimp contacts218 a and 218 b are fixed to both ends of the shape memory alloy member212. One crimp contact 218 a is fixed to a fixing pin 219 a planted on abase 126, the other crimp contact 218 b is fixed to an end of aresilient member 214. The other end of the resilient member 214 is fixedto a fixing pin 219 b planted on the base 216. A wiring portion 217 a(for example, a cable) of the energizing circuit 217 is connected to afixed end (the crimp contact 218 a) and a movable end (the crimp contact218 b) of the shape memory alloy member 212. The movable body (the crimpcontact 218 b) is displaced by causing the current to flow through theshape memory alloy member 212 by means of the energizing circuit 217.

However, in such a driving device 211 a, the crimp contact 218 b towhich the wiring portion 217 a of the energizing circuit 217 isconnected moves, and therefore it is necessary to provide a space or thelike so as to prevent an unnecessary external force from being exertedon the movable body (the crimp contact 218 b). Further, there is apossibility that the reliability of the electrical connection (bysoldering) between the wiring portion 217 a and the crimp contact 218 bmay decrease.

Further, in a driving device 211 b shown in FIG. 41(b), the shape memoryalloy member 212 is bent in V-shape. Crimp contacts 218 are fixed toboth ends of the shape memory alloy member 212, and the crimp contacts218 are fixed to two fixing pins 219 a planted on the base 216. Amovable body 213 is fixed to a bent portion of V-shape of the shapememory alloy member 212. The movable body 213 is fixed to an end of aresilient member 214, and the other end of the resilient member 214 isfixed to another fixing pin 219 b planted on the base 216. An energizingcircuit 217 is connected to two fixing pin 219 a, and supplies a currentto the shape memory alloy member 212 via the fixing pins 219 a and thecrimp contacts 218.

However, in such a driving device 211 b, the current flows through thecrimp contacts 218, and therefore portions of the shape memory alloymember 212 fixed to the crimp contacts 218 are repeatedly expanded andcontracted, with the result that the reliability of the connectingportion may decrease. Therefore, the problems such as the dropping ofthe shape memory alloy member 212 out of the crimp contacts 218 and thecutting of the shape memory alloy member 212 may easily occur.

In contrast, in the driving device 211 of this embodiment, the wiringportions of the energizing circuit 217 can be connected to the bendingmembers 215 a and 215 d, and therefore it is possible to prevent themovable body (the crimp contact 218 b) from being influenced by thewiring portions. Therefore, it is not necessary to provide a space orthe like around the wiring portions. Thus, it becomes possible tosimplify the configuration of the driving device 211, and to accomplishthe downsizing of the driving device 211. Further, since the currentdoes not flow through the crimp contacts 218 a and 218 b, the portionsof the shape memory alloy member 212 fixed to the crimp contacts 218 aand 218 b is not expanded or contracted. Therefore, the reliability ofthe connection between the crimp contacts 218 a and 218 b and the shapememory alloy member 212 is enhanced.

Embodiment 15.

FIG. 42 is a perspective view showing a configuration of a drivingdevice 221 a according to Embodiment 15 of the present invention. In theabove described Embodiment 14 (FIG. 40), the current is supplied throughthe bending members 215 d and 215 a respectively closest from themovable end and the fixed end of the shape memory alloy member 212. Inthis embodiment, an electric potential V1 is applied to a bending member225 a closest to the fixed end (the crimp contact 228 a) of the shapememory alloy member 222, and its adjacent bending member 225 b isgrounded. Further, an electric potential V2 is applied to a furtheradjacent bending member 225 c, and the bending member 225 d closest tothe movable end (the crimp contact 228 b) of the shape memory alloymember 222 is grounded. The electric potential V1 is applied to a pin229 a to which the crimp contact 228 a is fixed, so that a current doesnot flow through the crimp contact 228 a. Other configuration is thesame as Embodiment 14.

The bending members 225 a through 225 d constitute a bending means whichbends the shape memory alloy member 222. Portions of the circumferentialsurfaces of the bending members 225 a through 225 d contacting the shapememory alloy member 222 constitute a contact portion of the bendingmeans contacting the shape memory alloy member 222.

In the above described configuration, the current flows through asection of the shape memory alloy member 222 from the bending member 225c to the bending member 225 b, a section from the bending member 225 cto the bending member 225 d, and a section from the bending member 225 ato the bending member 225 b. As a result, each section of the shapememory alloy member 222 is heated and contracted, so that the movablebody (the crimp contact 228 b) is displaced.

That is, the current does not flow uniformly throughout the shape memoryalloy member 222, but flows respective sections independently. Theresistance to the current flowing through the respective sections of theshape memory alloy member 222 is smaller than the case where the currentflows uniformly. Therefore, even in the case of obtaining the samecurrent to that of Embodiment 14, the required voltage can be reduced.

Further, it becomes possible to select a portion through which thecurrent flows. For example, by setting the voltage applied to thebending member 225 a to 0, the current flows through two sides of theshape memory alloy member 222 (between the bending members 225 b and 225c and between the bending members 225 c and 225 d). With such anarrangement, only a portion of the shape memory alloy member 202 throughwhich the current flows is expanded and contracted, and therefore itbecomes to chose the amount of the displacement of the movable body (thecrimp contact 228 b).

In a configuration in which the amount of displacement is varied bycausing the current flows partially in the longitudinal direction of theshape memory alloy member, the method of electrical supply by supplyingelectricity via the contact between the shape memory alloy member andthe electric supply member such as pins (here, the bending members 225 athrough 225 b) is effective. There is another considerable method inwhich lead wires are attached to the shape memory alloy member. However,in such a case, it is necessary to attach a multiple lead wires in orderto increase the variation of the amount of displacement. Thus, in orderto prevent the shape memory alloy member from being influenced by theexternal force, it is necessary to provide a large space for disposingthe lead wires, and therefore the downsizing of the driving devicebecomes difficult. Further, if crimp contacts are used (in the casewhere the reliability of the soldering of the shape memory alloy memberis not high), there is a problem that a large space is needed as thenumber of the crimp contacts increases. In contrast, in this embodiment,the method of supplying electricity via pin-shaped bending members 225 athrough 225 d contacting the shape memory alloy member 222 is employed,it is not necessary to attach a multiple lead wires. Therefore, it ispossible to enable the selection of the amount of displacement, and toaccomplish the downsizing of the driving device.

In this embodiment, the shape memory alloy member 222 is wounded aroundthe pin-shaped bending members 225 a through 225 d (electrical supplymembers) at about 90 degrees for each. However, the winding angle is notlimited to about 90 degrees. Further, the bending members 225 a through225 are not limited to the pin-shape. Further, spring contacts or othercontacts can be used to connect the shape memory alloy member 222 andthe electrical supply members for electrical supply. With thesearrangement, it is possible to accomplish the downsizing of the drivingdevice.

Moreover, as shown in FIG. 43, in the case where the shape memory alloymember 222 is wound around the bending members 225 a through 225 d in aplurality of turns, the current flows the same sections (between thebending members 225 a and 225 b) of the shape memory alloy member 222 inparallel. Therefore, it is possible to provide the same electricalsupply as the case in which the shape memory alloy member 222 is woundaround the bending members 225 a through 225 d in one turn (FIG. 42).Further, since the entire length of the shape memory alloy member 222can be increased, it is possible to obtain a sufficient amount ofdisplacement of the movable body (the crimp contact 228 b) even when thederiving device 221 b is downsized.

As described above, according to this embodiment, since the currentflows through the respective sections of the shape memory alloy member222, it becomes possible to suppress the voltage to be low, and toenable the choosing of the amount of displacement of the movable body.Particularly, in a portable terminal such as a mobile phone device inwhich the available voltage is generally limited to be low, the drivingdevice according to this embodiment (operable at low voltage andsuitable for downsizing) is greatly valuable.

Embodiment 16.

FIG. 44 is a perspective view showing a driving device 231 a accordingto Embodiment 16 of the present invention. In the above describedEmbodiment 14, the current flows uniformly throughout the entire lengthof the shape memory alloy member 212. In contrast, in this embodiment,the current varies with sections of the shape memory alloy member 232.This is based on the consideration that a friction load applied to theshape memory alloy member 232 due to the contact with the othercomponents (in addition to the urging force of the resilient member 234)varies according to the position in the longitudinal direction of theshape memory alloy member 232.

An experiment providing the basis of this embodiment will be described.In the experiment shown in FIG. 45, the shape memory alloy member 232 inthe form of a wire is wound around a cylindrical bending member 235having a contact ratio of 33%. An energizing circuit 237 causes acurrent to flow only a straight portion of the shape memory alloy member232 (a portion not wound around the bending member 235). The length ofthe energized portion of the shape memory alloy member 232 is set to be50 mm. An end (fixed end) of the energized portion of the shape memoryalloy member 232 is fixed to the fixing pin 239 a. The amount ofdisplacement of the other end (a movable end 233) of the energizedportion is measured. Instead of a resilient member, a weight 234 a whichweighs 30 g is fixed to the movable end of the shape memory alloy member232 in order to prevent the change of the load. The bending member 235is made of POM, and is an approximately cylindrical member having adiameter of 10 mm whose contact ratio is 33% as shown in FIG. 36(b). Inorder to evaluate the influence of the friction load by winding theshape memory alloy member 232 around the bending member 235, theexperiment is carried out in a state where the shape memory alloy member232 is wound around the bending member 235 in one turn (360 degrees),two turns (720 degrees) and three turns (1080 degrees). As the number ofwindings increases, the friction load becomes large. Table 5 and FIG. 46show the result of the measurement of the amount R of displacement ofthe above described movable end 233 when the current value is variedfrom 60 mA to 180 mA. In FIG. 46, the vertical axis indicates the amountR (mm) of displacement of the above described movable end 233 of theshape memory alloy member 232, and the horizontal axis indicates acurrent I (mA) flowing through the shape memory alloy member 232.Moreover, marks a, b and c respectively correspond to data when theshape memory alloy member 232 is wound in one turn (360 degrees), twoturns (720 degrees), and three turns (1080 degrees). TABLE 5 WINDINGCURRENT VALUE ANGLE (mA) (degree) 60 80 100 120 140 160 180 360 0.0971.420 1.473 1.637 1.581 1.662 1.662 720 — 0.294 1.195 1.225 1.265 1.3441.423 1080  — 0.468 0.672 0.976 1.118 1.203 1.145

Based on Table 5 and FIG. 46, in the case (a) where the shape memoryalloy member 232 is wound in one turn, it is understood that there is anextreme point at about 80 mA of current I, and the amount R ofdisplacement does not change greatly when the current exceeds 80 mA.Moreover, in the case (b) where the shape memory alloy member 232 iswound in two turns, it is understood that there is an extreme point atabout 100 mA of current I, and the amount R of displacement does notchange greatly when the current exceeds 100 mA. In the case (c) wherethe shape memory alloy member 232 is wound in three turns, it isunderstood that there is an extreme point at about 160 mA of current,and the amount R of displacement does not change greatly when thecurrent exceeds 160 mA. Based on this result, it is understood that itis possible to suppress the power consumption of the driving device 231,and to obtain the almost maximum amount of displacement, by choosing theoptimum current according to the frictional force.

Based on this result, the driving device 231 a according to thisembodiment will be described. As shown in FIG. 44, in the driving device231 a according to this embodiment, four bending members 235 a, 235b,235 c and 235 d are disposed on a base 236 respectively on positionscorresponding to four tops of a rectangle. Inside the bending members235 a through 235 d, four bending members 235 e, 235 f, 235 g and 235 hare disposed. Inside the bending members 235 e through 235 h, fourbending member 235 i, 235 j, 235 k and 235 l are disposed. At asubstantial center of the base 236, a thirteenth bending member 235 mand a fixing pin 239 b are disposed.

The shape memory alloy member 232 in the form of a wire is wound aroundthe total thirteen bending members 235 a through 235 m on the base 236.That is, the shape memory alloy member 232 is wound around the mostoutside bending members 235 a through 235 d, then wound around theinside bending members 235 e through 235 h, then wound around furtherinside bending members 235 i through 235 l, and bent at the bendingmember 235 m. A crimp contact 239 d is fixed to an end (fixed end) ofthe shape memory alloy member 232, and the crimp contact 239 d is fixedto an end of a resilient member 234 in the vicinity of the outerperiphery of the base 236. The other end the resilient member 234 isfixed to a fixing pin 239 a planted on the base 236.

The bending member 235 a through 235 m constitute a bending means whichbends the shape memory alloy member 232. Portions of the circumferentialsurfaces of the bending members 235 a through 235 m contacting the shapememory alloy member 232 constitute a contact portion of the bendingmeans contacting the shape memory alloy member 232. The base 236constitutes a holding means which holds the bending members 235 athrough 235 m.

An electric potential Va is applied to the bending member 235 a closestto the movable end of the shape memory alloy member 232. The bendingmember 235 e at a position where the shape memory alloy member 232 iswound in one turn with respect to the bending member 235 a is grounded.In addition, an electric potential Vb is applied to the bending member235 i at a position where the shape memory alloy member 232 is wound intwo turns with respect to the bending member 235 a. The bending member235 k at the position where the shape memory alloy member 232 is woundin two turns and half is grounded. An electric potential Vc is appliedto the bending member 235 m closest to a fixed end of the shape memoryalloy member 232. As a result, a current Ia flows through the sectionfrom the bending member 235 a to the bending member 235 e of the shapememory alloy member 232. A current Ib flows through the section from thebending member 235 i to the bending member 235 e. Moreover, a current Icflows through the section from the bending member 235 i to the bendingmember 235 k. A current Id flows through the section from the bendingmember 235 m to the bending member 235 k. A conductive coil spring isused as the resilient member 234 so that the same voltage (Va) as thebending member 235 a is applied to the fixing pin 239 a, in order toprevent the current from flowing through the crimp contact 239 c.Moreover, the same voltage (Vc) as the bending member 235 m is appliedto the fixing pin 239 b, in order to prevent the current from flowingthrough the crimp contact 239 d. Since the current does not flow throughthe crimp contacts 239 c and 239 d as described above, the shape memoryalloy member 232 is not expanded and contracted at crimp portions 239 eof the crimp contacts 239 c and 239 d, and therefore the reliability ofthe connection is enhanced.

In the shape memory alloy member 232, the friction load when the currentflows becomes smaller, as the portion is closer to the movable end (thecrimp contact 239 c). Moreover, as the section through which the currentflows is long, the amount of displacement caused by the same current islarge, and therefore the necessary current becomes small with regard tothe same friction load. In the section from the bending member 235 a tothe bending member 235 e (the section where the current Ia flows), thefriction load is larger and the section length is shorter, compared withthe section from the bending member 235 e to the bending member 235 i(the section where the current Ib flows), and therefore the current Ibis set larger than the current Ia. Referring to the experiment result ofFIG. 46, the current Ia is set to, for example, 80 mA, and the currentIb is set to, for example, 100 mA. Further, in the section from thebending member 235 i to the bending member 235 k (the section where thecurrent Ic flows), the friction load is larger and the section length isshorter, compared with the section from the bending member 235 e to thebending member 235 i (the section where the current Ib flows), andtherefore the current Ic is set larger than the current Ib. Furthermore,in the section from the bending member 235 m to the bending member 235 k(the section where the current Id flows), the friction load is largerand the section length is almost the same, compared with the sectionfrom the bending member 235 i to the bending member 235 k (the sectionwhere the current Ic flows), and therefore the current Id is larger thanor equals to the current Ic. Referring to the experiment result of FIG.46, the current Ic and Id are set to, for example, 160 mA.

As described above, by changing the value of the current flowing throughthe shape memory alloy member 232 in consideration of the friction loadaccording to the winding position of the shape memory alloy member 232,it is possible to suppress a power consumption, and to obtain themaximum amount of displacement.

In the configuration shown in FIG. 44, although the movable end 239 c(and the resilient member 234) is disposed on the outermost side, thefixed end 239 d can be disposed on the outermost side and the movableend 239 c on the innermost side. However, it is possible to obtainlarger displacement at a low power consumption, when the movable end 239c is disposed on the outermost side. This is because, when the movableend 239 c is disposed on the outermost side, the length of the outerportion of the shape memory alloy member 232 becomes longer (andtherefore the amount of displacement becomes larger), and the summationof the load applied by the resilient member 234 and the friction loadapplied by the bending members becomes relatively small (with respect tothe amount of displacement), so that the required current for obtainingthe desired amount of displacement can be reduced.

FIG. 47 is a perspective view showing another example of electric supplyaccording to this embodiment. In the example shown in FIG. 47, thebending member 235 a is grounded, and an electric potential Va isapplied to the bending member 235 c at a position where the shape memoryalloy member 232 is wound a half. Similarly,. the bending member 235 eat a position where the shape memory alloy member 232 is wound in oneturn is ground. An electric potential Vb is applied to the bendingmember 235 g of the position where the shape memory alloy member 232 iswound in one turn and a half. In addition, the bending member 235 i at aposition where the shape memory alloy member 232 is wound in two turnsis grounded. An electric potential Vc is applied to the bending member235 k at a position where the shape memory alloy member 232 is wound intwo turns and half. In addition, the bending member 235 i at a positionwhere the shape memory alloy member 232 is wound in three turns isgrounded. As a result, the current Ia flows from the bending member 235c to the bending member 235 a, and the current Ib flows from the bendingmember 235 c to the bending member 235 e. Moreover, the current Ic flowsfrom the bending member 235 g to the bending member 235 e, and thecurrent Id flows from the bending member 235 g to the bending member 235i. In addition, the current Ie flows from the bending member 235 k tothe bending member 235 i, and the current If flows from the bendingmember 235 k to the bending member 235 m. The values of the respectivecurrent can be set as Ia≦Ib≦Ic≦Id≦Ie≦If. For example, based on theexperimental result of FIG. 46, the current Ia and the current Ib can beset to about 80 mA, the current Ic and the current Id can be set toabout 100 mA, and the current Ie and the current If can be set to about160 mA. In the example shown in FIG. 47, both of a constant voltagecircuit and a constant current circuit can be used as a power supplycircuit.

Moreover, instead of causing the current Ia through If to flow, it ispossible to cause the current to partially flow. With respect to theentire length of the shape memory alloy member 232, a part where thecurrent flows and a part where the current does not flow can beselectable, so that the amount of the displacement of the shape memoryalloy member 232 can be varied.

FIG. 48 is a perspective view showing a driving device 231 c accordingto this embodiment. The energizing circuit 237 c has constant currentcircuits 238 a, 238 b and 238 c. A terminal of the constant currentcircuit 238 a is connected to the bending member 235 m, and the otherterminal of the constant current circuit 238 a is connected to thebending member 235 a. A terminal of the constant current circuit 238 bis connected to the bending member 235 m, and the other terminal of theconstant current circuit 238 b is connected to the bending member 235 e.A terminal of the constant current circuit 238 c is connected to thebending member 235 m, and the other terminal of the constant currentcircuit 238 c is connected to the bending member 235 i. Between thebending member 235 m and the bending member 235 i, the constant currentcircuits 238 a, 238 b and 238 c cause the current Ia+Ib+Ic to flow.Between the bending member 235 i and the bending member 235 e, theconstant current circuits 238 a and 238 b cause the current Ia+Ib toflow. Between the bending member 235 e and the bending member 235 a, theconstant current circuits 238 a causes the current Ia to flow. That is,in the shape memory alloy member 232, the current flowing between thebending member 235 m and the bending member 235 i is the largest, thecurrent flowing between the bending member 235 i and the bending member235 e is the second largest, and the current flowing between the bendingmember 235 e and the bending member 235 a is the smallest. In concrete,considering the experimental result of FIG. 46, the largest current(Ia+Ib+Ic) can be set to 160 mA, the second largest current (Ia+Ib) canbe set to 100 mA, and the smallest current (Ia) can be set to 80 mA. Inthis case, the current Ib can be set to 20 mA, and the current Ic can beset to 60 mA.

FIG. 49 is a block diagram of the energizing circuit 237 c shown in FIG.48. As shown in FIG. 49, an entire length L of the shape memory alloymember 232 (the length from the bending member 235 a to the bendingmember 235 m) is set to be 15 mm. The length L3 between the bendingmembers 235 a and 235 e of the shape memory alloy member 232, the lengthL2 between the bending members 235 e and 235 i, and the length L1between the bending members 235 i and 235 m are respectively set to 5mm. The resistance of the shape memory alloy member 232 is set to 0.5Ω/mm. If the current Ia+Ib+Ic (160 mA) flows between the bending member235 m and the bending member 235 i of the shape memory alloy member 232,the current Ia+Ib (100 mA) flows between the bending member 235 i andthe bending member 235 e, and the current Ia (80 mA) flows between thebending member 235 e and the bending member 235 a,the entire powerconsumption is 0.105 W. In contrast, in a block chart of a comparativeexample shown in FIG. 50, when a constant current 160 mA flowsthroughout the entire length L (15 mm) of the shape memory alloy member232, the power consumption is 0.192 W. Base on this result, it isunderstood that it becomes possible to decrease the power consumption to55% by separately supplying the current as shown in FIG. 49.

FIG. 51 is a circuit diagram for illustrating the constant currentcircuits 238 a through 238 c shown in FIG. 48. In the constant currentcircuit 238 c, a resistance 238 d (R0) is a current value detectionresistance. When the current 238 e (IC) flows through the resistance 238d (R0), the potential difference of Ic×R0 is caused between both ends ofthe resistance 238 d (R0) This potential difference is an input voltageto a minus input terminal 238 g of an operational amplifier 238 f.Moreover, an input voltage (reference voltage) to a plus input terminal238 j of the operational amplifier 238 f is determined by a resistance238 h (R1) and a variable resistance 238 i (VR). The operationalamplifier 238 f operates to change the electric potential of aG-terminal 238 l of an FET (field-effect transistor) 238 k, and toadjust the current flowing from a D-terminal 238 m to a S-terminal 238 nso that the electric potential of the minus input terminal 238 g of theoperational amplifier 238 f is the same as the electric potential of theplus input terminal 238 j. As a result, the electric potential of theminus input terminal 238 g of the operational amplifier 238 f becomesconstant, and the current (Ic=V/R0) 238 e becomes constant, irrespectiveof the resistance of the shape memory alloy member 232. The constantcurrent circuits 238 a and 238 b operate in a similar manner to theconstant current circuit 238 c.

The constant current circuit 238 a though 238 c are described as beingsink-type circuits, but not limited to this. It is possible to use asource-type circuit. In this case, a ground electric potential isapplied to the bending member 235 m closest to the fixed end of theshape memory alloy member 2, and the directions of the respectivecurrents Ia, Ib and Ic are opposite to those shown in FIG. 49.

As described above, according to this embodiment, since the currentflows through the respective portions of the shape memory alloy member232 in accordance with the friction load or the like, it becomespossible to obtain a large amount of displacement at a small powerconsumption.

Embodiment 17.

FIG. 52 is a perspective view showing a configuration of a drivingdevice 241 a according to Embodiment 17 of the present invention. In theabove described Embodiments 14 through 16, the shape memory alloy memberis wound around a plurality of pin-shaped bending members, and thecurrent is supplied to the shape memory alloy member via the bendingmembers. In this embodiment, the pin-shaped bending members are furthermechanically and electrically connected to an electric circuit board.

As shown in FIG. 52, in the driving device 241 a, pin-shaped bendingmembers 245 a, 245 b, 245 c and 245 d are planted on an electric circuitboard 249 in such a manner that the bending members 245 a, 245 b, 245 cand 245 d are mechanically connected to the electric circuit board 249.Further, among the bending members 245 a, 245 b, 245 c and 245 d, atleast the bending members 245 a and 245 d are electrically connected tothe electric circuit board 249. Between the bending members 245 a and245 d, fixing pins 249 a and 249 b are planted in this order from theside closer to the bending member 245 a.

An end (fixed end) of the shape memory alloy member 242 is fixed to afixing pin 249 a by means of a crimp contact 248 a, and the shape memoryalloy member 242 is wound around the bending member 245 a, 245 b, 245 cand 245 d at 90 degrees for each. The other end (movable end) of theshape memory alloy member 242 is fixed to an end of the resilient member244 by means of a crimp contact 248 b, and the other end of theresilient member 244 is fixed to the fixing pin 249 b. Otherconfiguration is the same as Embodiment 14.

The bending members 245 a through 245 d constitute a bending means whichbends the shape memory alloy member 242. Portion of the circumferentialsurfaces of the bending members 245 a through 245 d contacting the shapememory alloy member 242 constitute a contact portion of the bendingmeans contacting the shape memory alloy member 242. The electric circuitboard 249 constitutes a holding means which holds the bending members245 a through 245 d.

In the above described configuration, the movable body (the crimpcontact 248 b) can be displaced by causing the current to flow throughthe shape memory alloy member 242 by means of the electric circuit board249 via the bending members 245 a and 245 d so that the shape memoryalloy member 242 is heated and contracted.

According to this embodiment, the bending members 245 a through 245 dare held by the electric circuit board 249, and therefore it is notnecessary to provide a separate base. Thus, the number of components canbe reduced, with the result the downsizing of the driving device can beeasily accomplished. Particularly, if this driving device 241 a isapplied to the above described Embodiments 14 through 16 (FIGS. 40, 42through 44 and 47 through 48), it becomes possible to form theenergizing circuit (for example, the energizing circuit 237 of FIG. 40or the energizing circuit 217 c of FIG. 48) on the electric circuitboard 249. Therefore, it becomes easy to supply electricity to thebending members 215, 225 and 235 (FIGS. 40, 42 through 44 and 47 through48). Moreover, since the bases 216, 226 and 236 (FIGS. 40, 42 through 44and 47 through 48) can be composed of the electric circuit board 249,the number of components can be reduced, and the downsizing of thedriving device can be easily accomplished.

FIG. 53 is a perspective view showing another configuration example ofthe driving device according to this embodiment. In the driving device241 b shown in FIG. 53, the bending members 245 a, 245 b, 245 c and 245d are planted on the base 246. Between the bending members 245 a and 245d, the fixing pins 249 a and 249 b are planted in this order from theside closer to the bending member 245 a. An end (fixed end) of the shapememory alloy member 242 is fixed to the fixing pin 249 a by means of thecrimp contact 248 a, and the shape memory alloy member 242 is woundaround the bending member 245 a, 245 b, 245 c and 245 d at abut 90degrees for each. The other end (movable end) of the shape memory alloymember 242 is fixed to an end of a resilient member 244 by means of acrimp contact 248 b, and the other end of the resilient member 244 isfixed to the fixing pin 249 b.

In the driving device 241 b shown in FIG. 53, in addition, an electriccircuit board 249 is provided on the side opposite to the base 246 withrespect to the shape memory alloy member 242. The bending members 245 athrough 245 d are mechanically connected to the electric circuit board249. The pin-shaped bending members 245 a through 245 d engage fourpenetration holes punched on the electric circuit board 249. Moreover,among the bending members 245 a through 245 d, the bending members 245 aand 245 d needed for energizing the shape memory alloy member 242 areelectrically connected to electric circuit board 249. It is alsopossible to connect all bending members 245 a through 245 d to theelectric circuit board 249 electricity and mechanically.

In the above described driving device 241 a of FIG. 52, the bendingmembers 245 a through 245 d are connected to the electric circuit board249. Therefore, when the driving force generated by the expansion andcontraction of the shape memory alloy member 242 is relatively small,the bending members 245 a through 245 d can be stably held. However,when the driving force generated by the expansion and contraction of theshape memory alloy member 242 is relatively large, it is difficult tostably hold the bending members 245 a through 245 d, and therefore thereliability of the electric connection may decrease. In contrast,according to the driving device 241 b shown in FIG. 53, the bendingmember 245 a through 245 d are held by the base 246, and therefore it ispossible to stably hold the bending members 245 a through 245 d bydesigning the base 246 according to the load exerted on the bendingmembers 245 a through 245 d. Moreover, the mechanical connection of theelectric circuit board 249 a nd the bending members 245 a through 245 dhelps the electric circuit board 249 to hold the bending members 245 athrough 245 d, and therefore it is possible to stably hold the bendingmembers 245 a through 245 d even when the force exerted on the bendingmembers 245 a through 245 d is relatively large. Moreover, by placingthe electric circuit board 249 on the side opposite to the base 246 withrespect to the shape memory alloy member 242, it is possible to preventthe shape memory alloy member 242 from dropping out of the bendingmembers 245 a through 245 d.

In the case of the driving device 241 b, it is also possible to use aseat-like flexible board, so-called the FPC (Flexible Printed Circuit)board, because the electric circuit board 249 is not needed to have astrength.

Embodiment 18.

FIG. 54 is a perspective view showing the configuration of a drivingdevice 251 according to Embodiment 18 of the present invention. In theabove described Embodiments 14 through 17, the shape memory alloy memberis wound around the pin-shaped bending members (for example, the bendingmembers 215 a through 215 d shown in FIG. 40). In contrast, in thedriving device 251 according to this embodiment, a shape memory alloymember 252 is wound around a bending member 252 composed of a structuralbody made of a non-conductive member (for example, a plastic) on which aconductive member is formed.

As shown in FIG. 54, the driving device 251 has a bending member 255made by forming four approximately cylindrical projections 255 a through255 d on four corners of a structural body 255 e made of an insulationmaterial (for example, a plastic) in the form of, for example, aquadrangular column. On a surface of the projections 255 a and 255 dside of the bending member 255, fixing members 258 b and 258 a areformed in this order from the side closer to the projection 255 a. Anend (fixed end) of the shape memory alloy member 252 is fixed to thefixing member 258 b of the bending member 255, and the shape memoryalloy member 252 is wound around the projections 255 a, 255 b, 255 c and255 d at 90 degrees for each. The other end (movable end) of the shapememory alloy member 252 is fixed to an end of the resilient member 254via a movable body 253, and the other end of the resilient member 254 isfixed to the fixing member 258 a.

The bending member 255 has a conductive member 259 a on the projection255 a closest from the fixed end of the shape memory alloy member 252,and has another conductive member 259 b on the projection 255 d closestfrom the movable end of the shape memory alloy member 252. An energizingcircuit 257 is connected to the conductive members 259 a and 259 b. Theenergizing circuit 257 causes the current to flow through the shapememory alloy member 252 via the conductive members 259 a and 259 b, sothat the shape memory alloy member 252 is heated and the movable member253 fixed to the movable end is displaced. Although the energizingcircuit 257 is illustrated to be apart from the bending member 255 inFIG. 54, it is possible to form the energizing circuit 257 on thesurface of the bending member 255, and to form a solid circuit board.

The bending member 255 having the projections 255 a through 255 dconstitute a bending means which bends the shape memory alloy member252. Portions of the circumferential surfaces of the projections 255 athrough 255 d contacting the shape memory alloy member 252 constitute acontact portion of the bending means contacting the shape memory alloymember 252. The bending member 255 constitutes a holding means whichholds the projections 255 a through 255 d.

In the above described configuration, the movable body 253 can bedisplaced by causing the current to flow through the shape memory alloymember 252 by means of the energizing circuit 257 via the bendingmembers 259 a and 259 b so that the heating shape memory alloy member252 is heated and contracted.

According to this embodiment, since the shape memory alloy member 252 iswound around the contact portions 258 a through 258 d integrally formedwith the bending member 255, it is possible to enhance the rigidity ofthe contact portions 258 a through 258 d. Therefore, even when a loadapplied to the contact portions 258 a through 258 d is large, it ispossible to prevent the deformation of the contact portions 258 athrough 258 d, and to enhance the reliability of the electricalconnection between the conductive members 259 a and 259 b and theenergizing circuit 257. Particularly, compared with the case in whichthe shape memory alloy member 252 is wound around pin-shaped bendingmembers (for example, FIG. 52), the strength of the mechanicalconnection between the energizing circuit 257 and the conductive members259 a and 259 b is high, and the reliability of the electricalconnection is high. Further, since the energizing circuit 257 is formedon the bending member 255 to form a solid circuit, it is not necessaryto employ a configuration in which the pin-shaped bending members 245 athrough 245 d is sandwiched between the base 246 and the electriccircuit board 249 a shown in FIG. 53. As a result, it is possible toaccomplish the downsizing of the driving device, while maintaining thereliabilities of the electrical connection and the mechanicalconnection.

Embodiment 19.

FIG. 55 is a perspective view showing the configuration of a drivingdevice 261 a according to Embodiment 19 of the present invention. In thedriving device 261 a shown in FIG. 55, a bending member 265 arespectively in the form of a cylinder having minute convex portions 265e on the circumferential surface thereof is rotatably supported on abase 266. An end (fixed end) of a shape memory alloy member 262 is fixedto a fixing pin 269 a provided on the base 266, and the shape memoryalloy member 262 is wound around the bending member 265 a at about 180degrees in such a manner that the shape memory alloy member 262 contactsthe convex portions 265 e of the bending member 265 a. The other end(movable end) of the shape memory alloy member 262 is fixed to an end ofa resilient member 264 via a movable body 263, and the other end of theresilient member 264 is fixed to a fixing pin 269 b planted on the base266. The energizing circuit 267 is connected with the fixing pins 269 aand 269 b. Other configuration is the same as Embodiment 1.

The bending member 265 a constitutes a bending means which bends theshape memory alloy member 262. Portions of the convex portions 265 e ofthe bending member 265 a contacting the shape memory alloy member 262constitutes a contact portion of the bending means contacting the shapememory alloy member 262. The base 266 constitutes a holding member forholding the bending member 265 a.

In the above described configuration, the movable body 263 can bedisplaced by causing the current to flow through the shape memory alloymember 262 by means of the energizing circuit 267 via the fixing pins269 a and 269 b so that the shape memory alloy member 262 is heated andcontracted.

FIGS. 56(a) through (c) are perspective views showing experimentalarrangements 261 b, 261 c and 261 d for verifying the effect of thedriving device 261 a. In the experimental arrangement 261 b shown inFIG. 56(a), a wire-shaped memory alloy member 262 is wound around acylindrical bending member 265 b having a diameter of 10 mm which is notrotatable and which has no convex portions. An end (fixed end) of theshape memory alloy member 262 is fixed to a fixing pin 269 a, and aweight 264 a which weighs 50 g is fixed to the other end (movable end)of the shape memory alloy member 262. When the energizing circuit 267causes a direct current of 140 mA to flow through an area of the shapememory alloy member 262 including a portion wound around the bendingmember 265 b, the amount of displacement of the movable end of the shapememory alloy member 262 is measured. In the experimental arrangement 261c shown in FIG. 56(b), a cylindrical bending member 265 c having adiameter of 10 mm which has no convex portion is rotatably supported onthe base 266, and the other conditions are the same as those of theexperimental arrangement 261 b of FIG. 56(a). In the experimentalarrangement 261 d shown in FIG. 56(c), a bending member 265 d having adiameter of 10 mm which has convex portions 265 e on the circumferentialsurface thereof is rotatably supported on the base 266, and the otherconditions are the same as those of the experimental arrangement 261 bof FIG. 56(b). The contact ratio of the bending member 25 (ratio of alength with which the convex portion 265 e contacts the shape memoryalloy member 262 with respect to an entire circumferential length of thebending member 265 d) is 33%. The bending members 261 b, 261 c and 261 dshown in FIGS. 56(a) through (c) are made of POM.

Using the experimental apparatuses shown in FIGS. 56(a) through (c), theamount of displacement on a movable end of the shape memory alloy member262 is measured on condition that the winding angle is set to 360degrees (one turn), 450 degrees (1 turn and half) and 720 degrees (twoturns). A further experiment is carried out on condition that therotation of the bending member 265 d is locked in the experimentalarrangement 261 d shown in FIG. 56(c). The result thereof is shown inTable 6 and FIG. 57. In FIG. 57, the vertical axis indicates adisplacement ratio H (%), and the horizontal axis indicates a windingangle θ (degrees). In FIG. 57, the mark a indicates the data when thenon-rotatable cylindrical bending member 265 b (FIG. 56(a)) is used. Themark b indicates the data when the rotatable cylindrical bending member265 c (FIG. 56(b)) is used. The mark c indicates the data when thenon-rotatable bending member (not shown) having a contact ratio of 33%(FIG. 56(c)) is used. The mark d indicates the data when the rotatablebending member 265 b having a contact ratio of 33% (FIG. 56(c)) is used.TABLE 6 ROTATION OF DISPLACEMENT RATIO (%) BENDING MEMBER 1.5 (CONTACTRATIO) 1 TURN TURNS 2 TURNS AVERAGE NON-ROTATABLE 69.2 56.0 51.8 59.0(33%) ROTATABLE 79.0 70.2 68.1 72.4 (33%) NON-ROTATABLE 24.8 26.6 25.325.6 (100%) ROTATABLE 30.9 41.1 38.8 36.9 (100%)

Based on FIG. 57, it is understood that, when the rotatable bendingmember 265 c (the mark b) is used instead of the non-rotatable bendingmember 265 b (the mark a), the displacement of the shape memory alloy262 increases approximately 1.2 to 1.5 times. Moreover, when therotatable bending member 265 d (the mark d) having the contact ratio of33% is used, the displacement of the shape memory alloy 262 increasesapproximately 2.7 to 3.2 times.

Based on the above described result, according to this embodiment, itbecomes possible to increase the amount of displacement of the movablebody 263 by using the rotatable bending member 261 a having convexportions on the circumferential surface thereof. While the drivingdevices having wire-shaped shape memory alloy members wound aroundpulleys are disclosed in Japanese Laid-Open Patent Publication Nos. HEI8-776743 and HEI 10-148174, it becomes possible to obtain a large amountof displacement by forming convex portions on these pulleys so as toreduce the contact ratio.

The rotatable bending member is not limited to a cylindrical shape, butcan be in the form of a polygonal column such as a triangular column aswas described in Embodiment 12, and further can be made of a pluralityof pins disposed along a closed path.

Embodiment 20.

FIG. 58 is a perspective view showing the configuration of a drivingdevice 271 a according to Embodiment 20 of the present invention. Thedriving device 271 a according to this embodiment is different from thedriving device 261 a (FIG. 55) according to Embodiment 19 in that ashape memory alloy member 272 is wound around a pin 279 c planted on acircumferential surface of the bending member 275 a.

As shown in FIG. 58, the driving device 271 a has a rotatable bendingmember 275 a in the form of an approximately cylindrical shape having alot of minute convex portions 275 e formed on the circumferentialsurface thereof. On the circumferential surface of this bending member275 a, a pin (protrusion) 279 c is provided, in addition to the convexportion 275 e. The pin 279 c protrudes in the radial direction of thebending member 275 a, in addition to the convex portion 275 e. An end(fixed end) of the shape memory alloy member 272 in the form of a wireis fixed to a fixing pin 279 b on a base 276 by means of a crimp contact278 b. The shape memory alloy member 272 is wound around bending member275 a at, for example, 360 degrees. Moreover, the shape memory alloymember 272 is also wound around the pin 279 c at, for example, 360degrees while the shape memory alloy member 272 is wound around thebending member 275 a. The other end (movable end) of the shape memoryalloy member 272 is fixed to an end of a resilient member 274 by meansof a crimp contact 278 a, and the other end of resilient member 274 isfixed to a fixing pin 279 a formed on the base 276.

The bending member 275 a constitutes a bending means which bends theshape memory alloy member 272. The pin 279 c constitutes a protrusionthat protrudes from the bending member 275 a so that the shape memoryalloy member 272 is wound around the pin 279 c. Portions of the convexportions 275 e of the bending member 275 a contacting the shape memoryalloy member 272 constitute a contact portion of the bending meanscontacting the shape memory alloy member 272. The base 276 constitutes aholding means which holds the bending member 275 a.

In the above described configuration, the movable body (the crimpcontact 278 a) can be displaced by causing the current to flow throughthe shape memory alloy member 272 by means of an energizing circuit 277so that the shape memory alloy member 272 is heated and contracted. Withthis, the bending member 275 a also rotates. When the current flowingthrough the shape memory alloy member 272 is stopped, the shape memoryalloy member 272 is cooled and expanded to its original length, so thatthe movable body (the crimp contact 278 a) returns to its originalposition, and the bending member 275 a returns to its originalrotational position.

Although the above described Embodiment 19 (FIG. 55) is effective whenthe rotational position of the bending member 265 can be arbitrary as apulley, this embodiment is effective when the rotational position of thebending member 265 is limited.

FIG. 59 is a perspective view showing an experimental arrangement 271 bfor measuring the amount of displacement of the movable body of thedriving device 271 a according to Embodiment 20. The experimentalarrangement 271 b includes a bending member 275 b rotatably provided ona base 276, and the bending member 275 b has convex portions and a pin279 c on the circumferential surface thereof. The contact ratio of thebending members 275 b is 33%. An end (fixed end) of the shape memoryalloy member 272 is fixed to a fixing pin 279 b fixed to the base 276 bymeans of a crimp contact 278 b. The shape memory alloy member 272 iswound around the bending member 275 b at about 360 degrees, then woundaround the pin 279 c at about 360 degrees, and further wound around thebending member 275 b at about 360 degrees. The other end (movable end)of the shape memory alloy member 272 is fixed to an end of a resilientmember 274 composed of a coil spring by means of a crimp contact 278 a,and the other end of the resilient member 274 is fixed to a fixing pin279 a planted on the base 276. An energizing circuit 277 is connected tothe fixing pins 279 a and 279 b, so that a current flows through theshape memory alloy member 272 via the fixing pins 279 a and 279 b. Theshape memory alloy member 272 has a diameter of about 60 μm and a lengthof about 83 mm. The urging force of the resilient member 274 is about392×10⁻³ N when the shape memory alloy member 272 is not energized. Thecurrent caused to flow through the shape memory alloy member 272 bymeans of the energizing circuit 277 is 140 mA. The length c of the shapememory alloy member 272 from the bending member 275 b to the crimpcontact 278 a is about 1.5 mm.

Using the experimental arrangement shown in FIG. 59, the amount ofdisplacement of the crimp contact 278 a (when the energizing is carriedout by the energizing circuit 277) is measured. Additionally, the amountof displacement is measured also in the case where the shape memoryalloy member 272 is not wound around the pin 279 c, or in the case wherethe rotation of the bending member 275 b is locked. The result thereofis shown in Table 7 and FIG. 60. In FIG. 60, the vertical axis indicatesthe displacement ratio H (%). In the horizontal axis, the mark bindicates data in the case where the shape memory alloy member 272 iswound around the pin 279 c as shown in FIG. 59. The mark a indicatesdata in the case where the shape memory alloy member 272 is not woundaround the pin 279 c. The mark c indicates data in the case where therotation of the bending member 275 b is locked (the shape memory alloymember 272 is not wound around the pin 279 c). TABLE 7 BENDING MEMBERWINDING ROTATABLE/ DISPLACEMENT AROUND PIN NOT ROTATABLE RATIO (%)WINDING ROTATABLE 56.9 NO WINDING ROTATABLE 53.5 NO WINDING NOTROTATABLE 46.8

Based on FIG. 60, it is understood that it is possible to obtain thealmost same amount of displacement when the shape memory alloy member272 is wound around the pin 279 c (mark b) and when the shape memoryalloy member 272 is not wound around the pin 279 c (mark a) . Moreover,it is understood that in both of these cases (marks a and b), it ispossible to obtain a larger amount of displacement than in the casewhere the rotation of the bending member 275 b is locked (mark c) . Thatis, it is understood that the decrease in the amount of displacement dueto the winding of the shape memory alloy member 272 around the pin 279 c(i.e., the fixing of the shape memory alloy member 272 to the bendingmember 275) is very small, and almost the same advantage as Embodiment19 can be obtained.

As described above, according to this embodiment, it is possible toobtain the same advantage as Embodiment 19 even in the case where therotational position of the bending member 275 is limited (notarbitrary).

The rotatable bending member 275 a is not limited to the cylindricalshape, but may be in the form of a polygonal column such as a triangularcolumn as was described in Embodiment 12. In such a case, it is possibleto obtain the same advantage.

Embodiment 21.

FIG. 61(a) is a perspective view of a configuration example (referred toas a driving device 281 a)in the case where the driving devices 1, 11,21 and 31 (FIGS. 1, 2 and 9 through 11 ) are applied to a lens drive ina camera. The camera to which this driving device 281 a is applied has acylindrical barrel 286 a and a circuit board 289 d provided on a side(rear side) of the barrel 286 a opposite to an object. A lens 283 e(FIG. 64(a)) is fixed to a tip of the barrel 286 a. A lens 283 b (FIG.64(a)) held by a lens frame 283 a is provided in the barrel 286 a. Thelens frame 283 a is movably supported by guide axes 283 c and 283 d(FIG. 64(a)) along an optical axis X of the lens. A part of the lensframe 283 a penetrates a groove axially formed on the barrel 286 a andprojects outward. Moreover, the circuit board 289 d has a solid stateimage sensing device 289 c (FIG. 64(a)) at a position where the image isfocused by lens 283 e and 283 b.

On the circumferential surface of the barrel 286 a, a plurality ofpin-shaped bending members 285 are planted. These bending members 285are disposed at intervals in a circumferential direction of the barrel286 a. The bending member 285 has a main part that projects in theradial direction of the barrel 286 a and an orthogonal member thatprojects from the main part in the direction almost parallel to theaxial direction of the barrel 286 a.

An end (fixed end) of a shape memory alloy member 282 in the form of awire is fixed to a fixing member 289 b in the vicinity of the rear endof the barrel 286 a. The shape memory alloy member 282 turns around thebarrel 286 a almost in one turn in such a manner that the shape memoryalloy member 282 is wound around the bending members 285, and furtherextends in the axial direction of the barrel 286 a. The other end(movable end) of the shape memory alloy member 282 is fixed to the rearend of the above described lens frame 283 a. An end of a resilientmember 284 is fixed to a front end of the lens frame 283 a, and theother end of this resilient member 284 is fixed to a fixing member 289 aprovided in the vicinity of the front end of the barrel 286 a. Anenergizing circuit 287 is connected to both ends of the shape memoryalloy member 282.

When the energizing circuit 287 causes the current to flow through theshape memory alloy member 282 to heat the shape memory alloy member 282,the shape memory alloy member 282 is contracted resisting the urgingforce of the resilient member 284, so that the lens frame 283 a movesrearward (direction of an arrow A) . When the energizing of the shapememory alloy member 282 is stopped, the shape memory alloy member 282 iscooled and expanded to its original length, so that the lens frame 283 amoves frontward (direction of an arrow B) by means of the urging forceof the resilient member 284. As a result, the lens 283 b (FIG. 64(a))moves in the direction of the optical axis X, and, for example, azooming operation or a focusing operation is carried out.

As constructed above, it becomes possible to dispose the shape memoryalloy member 282 whose entire length is long (i.e., a amount ofdisplacement is large) around the barrel 286 a without increasing thelength of the barrel 286 a of the camera. Moreover, since the shapememory alloy member 282 is wound around the pin-shaped bending members285, it is possible to reduce the ratio of the length with which theshape memory alloy member 282 contacts the bending members 285 to theentire circumferential length of the barrel 286 a (i.e., a contactratio). As a result, it is possible to reduce the decrease in the amountof displacement, compared with the case in which the shape memory alloymember 282 is linearly disposed.

FIG. 61(b) is a perspective view showing a configuration example(referred to as a driving device 281 b)in the case where the drivingdevice 51 (FIG. 14) of Embodiment 6 is applied to the lens drive of thecamera. In this driving device 281 b, a large number of convex portions285 b similar to the convex portions 54 a (FIG. 14) described inEmbodiment 6 are formed in the circumferential direction of the barrel286 a. Only one bending member 285 a, for example, is formed on the rearside of the lens frame 283 a. An end (fixed end) of the shape memoryalloy member 282 is fixed to a fixing member 289 b, and the shape memoryalloy member 282 is wound around the barrel 286 a in almost one turn insuch a manner that the shape memory alloy member 282 contacts the convexportions 285 b, and then the shape memory alloy member 282 is woundaround the bending member 285 a at about 90 degrees. The other end(movable end) of the shape memory alloy member 282 is fixed to the lensframe 283 a. Each convex portion 285 b is elongated in the axialdirection of the barrel 286 a. Other configuration is the same as thedriving device 281 a shown in FIG. 61(a).

Using the driving device 281 b, it becomes possible to dispose the shapememory alloy member 282 whose entire length is long (i.e., a amount ofdisplacement of the movable end is large) around the barrel 286 awithout increasing the length of the barrel 286 a of the camera.Moreover, since the shape memory alloy member 282 is wound around thebending member 285 a and the convex portion 285 b, it is possible toreduce the ratio of the length with which the shape memory alloy member282 contacts the bending member 285 a and the convex portions 285 b tothe entire circumferential length of the barrel 286 a (i.e., a contactratio). As a result, it is possible to reduce the decrease in the amountof displacement, compared with the case in which the shape memory alloymember 282 is linearly disposed.

FIG. 62(a) is a perspective view showing a configuration example(referred to as a driving device 281 c)in the case where the drivingdevice 261 a (FIG. 55) of Embodiment 18 is applied to the lens drive ofthe camera. In this driving device 281 c, a cylindrical ring 285 c isprovided on the circumference of the barrel 286 a, and the cylindricalring 285 c is rotatable in the circumferential direction of the barrel286 a. A number of convex portions 285 b described with reference toFIG. 61(b) are formed on a circumference of the cylindrical ring 285 cat intervals in the circumferential direction of the cylindrical ring285 c. An end (fixed end) of the shape memory alloy member 282 is fixedto a fixing member 289 b. The shape memory alloy member 282 is woundaround the cylindrical ring 285 c in almost one turn in such a mannerthat the shape memory alloy member 282 contacts the convex portions 285b, and then the shape memory alloy member 282 is wound around thebending member 285 a at about 90 degrees. The other end (movable end) ofthe shape memory alloy member 282 is fixed to the lens frame 283 a. Thecylindrical ring 285 c has a cutaway portion 285 f in order not tointerfere with the fixing member 289 b when the cylindrical ring 285 crotates. Other configuration is the same as the driving device 281 bshown in FIG. 61(b).

According to this driving device 281 c, the contact ratio is small andthe cylindrical ring 285 c is rotatable, and therefore it is possible toincrease the amount of displacement of the shape memory alloy member 282as was described in Embodiment 18.

FIG. 62(b) is a perspective view showing a configuration example(referred to as a driving device 281 d)in the case where the drivingdevice 271 a (FIG. 58) of Embodiment 19 is applied to the lens drive ofthe camera. In this driving device 281 d, the pin-shaped bending member285 e is planted on the circumferential surface of the cylindrical ring285 d, and is located behind the bending member 285 a planted on thecircumferential surface of the barrel 286 a. The shape memory alloymember 282 is wound around the convex portions 285 b to turn around thecylindrical ring 285 c in ¼ turn, and then wound around the bendingmember 285 e. The shape memory alloy member 282 is further wound aroundthe convex portions 285 b to turn around the cylindrical ring 285 c inalmost one turn, and-then bent by the bending member 285 at 90 degrees.Other compositions are the same as those of the driving device 281 cshown in FIG. 62(a).

According to the driving device 281 d, the positional relationshipbetween the shape memory alloy member 282 and the cylindrical ring 285 dis regulated by the pin-shaped bending member 285 e, and therefore therotational position of the cylindrical ring 285 d does not deviate evenif the shape memory alloy member 282 is repeatedly expanded andcontracted. Therefore, it is possible to keep constant the positionalrelationship between the fixing member 289 b that fixes the fixed end ofthe shape memory alloy member 282 and the cutaway portion 285 f of thecylindrical ring 285 d.

FIGS. 63(a) and (b) are a perspective view and a front view showing aconfiguration example (referred to as a driving device 281 e) in thecase where the driving devices 41 and 151 of Embodiments 5 and 11 (FIGS.12 and 26) is applied to the lens driving of the camera. FIG. 63(c) isanother perspective view of the driving device 281 e seen from thedirection different from FIG. 63(a).

As shown in FIGS. 63(a) and (b), the driving device 281 e has a bendingmember 285 g formed in the vicinity of the front end of a barrel 286 a,and a bending member 285 f formed in the vicinity of the rear end of thebarrel 286 a. The lens frame 283 a is disposed between the bendingmembers 285 g and 285 f in the axial direction of the barrel 286 a. Abending member 285 h is formed on and projects from the circumferentialsurface of the barrel 286 a, and is located on a further front positionwith respect to the bending member 285 g. A number of minute convexesare formed on the circumferential surfaces of the bending members 285 g,285 f and 285 h, which contact the shape memory alloy member 282. On thecircumferential surface of the barrel 286 a,a fixing member 289 b isdisposed on a position shifted from the lens frame 283 a in thecircumferential direction of the barrel 286 a. A fixing member 289 a isprovided between the lens frame 283 a and the bending member 285 g. Aresilient member 284 is provided between the fixing member 289 a and thelens frame 283 a.

An end (fixed end) of the shape memory alloy member 282 is fixed to thefixing member 289 b (FIG. 63(c)). The shape memory alloy member 282 isled frontward from the fixing member 289 b in the axial direction of thebarrel 286 a. In the vicinity of the front end of the barrel 286 a, theshape memory alloy member 282 is bend by the bending member 285 g atabout 180 degrees, and is led rearward almost in the axial direction ofthe barrel 286 a. Moreover, the shape memory alloy member 282 is woundby the bending member 285 f at about 180 degrees in the vicinity of therear end of the barrel 286 a, and is led frontward almost in the axialdirection of the barrel 286 a. The other end (movable end) of the shapememory alloy member 282 is fixed to the lens frame 283 a. As shown inFIG. 63(b), where the shape memory alloy member 282 is wound around thebending member 285 g at 180 degrees, the shape memory alloy member 282also contacts the bending member 285 h, so that the shape memory alloymember 282 does not contact the circumferential surface of the barrel286 a.

According to the driving device 286 a, it is possible to dispose theshape memory alloy member 282 whose entire length is long (i.e., theamount of displacement of the movable end is large) around the barrel286 a without increasing the length of the barrel 286 a of the camera.Moreover, because the shape memory alloy member 282 is wound around thebending member 285 h, 285 g, and 285 f having minute convex portions onthe outer sides thereof, it is possible to suppress the decrease in theamount of displacement.

In the above described Embodiment 12, it has been described that, if thebending member is in the form of a polygonal column, an almosttriangular column (whose cross section is almost triangle) ispreferable. However, if the bending member is not in the form of thepolygonal column, the configuration in which the shape memory alloymember is wound around two bending members is advantageous in terms ofreducing the contact ratio (to thereby suppress the decrease in theamount of displacement) while keeping the contact length between onebending member and the shape memory alloy member as was described inEmbodiment 3. The above described driving device 281 e is an example ofsuch a configuration being applied to the lens driving.

Next, in order to facilitate the understanding of the effect of thedriving device according to this embodiment, a configuration example inthe case where a driving device in which a shape memory alloy member islinearly disposed is used for driving the lens in the camera will bedescribed.

FIGS. 64(a) and (b) are a side sectional view and a perspective viewshowing the configuration example (referred to a driving device 281 f)in the case where the driving device in which the shape memory alloymember 2 is linearly disposed is used for driving the lens of thecamera. In this driving device 281 f, an end (fixed end) of a shapememory alloy member 282 is fixed to a fixing member 289 b provided inthe vicinity of the rear end of the barrel 286 a and the other end(movable end) of the shape memory alloy member 282 is fixed to a lensframe 283 a. A fixing member 289 a is provided in the vicinity of thefront end of the barrel 286 a, and a resilient member 284 is providedbetween the fixing member 289 a and the lens frame 283 a. An energizingcircuit 287 is connected to both ends of the shape memory alloy member282. However, in such a configuration, because the shape memory alloymember 282 is linearly disposed on the barrel 286 a, only a shape memoryalloy member 282 whose entire length is short can be provided in thecamera whose length is short in the direction of the barrel 286 a.Moreover, if the shape memory alloy member 282 whose entire length isshort is provided, there is a problem that a sufficient driving distanceof the lens 283 b can not be obtained, since the amount of displacementof the shape memory alloy member 282 is about 3 through 5% with respectto the entire length of the shape memory alloy member 282.

In contrast, according to the driving device 281 a (FIG. 61(a)) of thisembodiment and the driving devices 281 b through 281 e (FIGS. 61(b)through 63(c)) of other example of this embodiment, the shape memoryalloy member 282 whose entire length is long can be wound around thecircumferential surface of the barrel 286 a by means of the bendingmember 285 (or the bending members 285 a through 285 h). Therefore, evenin a small-sized camera, there is an advantage that a sufficient drivinglength of the lens 283 b is ensured by using the shape memory alloymember 282 whose entire length is long.

In the above described Embodiments 1 through 21, although the shapememory alloy member is heated and deformed by causing the direct currentto flow through the shape memory alloy member, the embodiments are notlimited to this. It is also possible to use an alternating currentinstead of the direct current. Moreover, it is possible to cause a pulsecurrent to flow through the shape memory alloy member to heat the shapememory alloy member as disclosed in Japanese Laid-Open PatentPublication No. HEI 6-324740, and it is possible to use a heater to heatthe shape memory alloy member as disclosed in Japanese Laid-Open PatentPublication No. HEI 6-32296. Furthermore, it is possible to use othercomponents to heat the shape memory alloy member, as disclosed inJapanese Laid-Open Patent Publication No. HEI 5-224136. Further, it ispossible to heat the shape memory alloy member by means of a change inenvironmental temperature, as disclosed in Japanese Laid-Open PatentPublication Nos. 2000-318698, HEI 5-118272, 2003-28337, HEI 7-14376 andHEI 8-179181.

Moreover, in a configuration in which the shape memory alloy member isbent by the bending member and is heated to obtain the amount ofdisplacement, the decrease in the amount of displacement is large whenthe contacting part between the shape memory alloy member and thebending member is large, and the decrease in the amount of displacementis small when the contacting part between the shape memory alloy memberand the bending member is small, as described above. This seems to bebecause, in the contacting part between the shape memory alloy memberand the bending member, the heat is drawn from the shape memory alloymember via the bending member, so that the temperature increase of theshape memory alloy member is suppressed. With consideration given tothis, it is effective to heat the shape memory alloy member byenergizing in terms of obtaining a large amount of displacement.Moreover, in the case where the temperature increase of the bendingmember is slow (in the case where the heat of the shape memory alloymember does not tend to be drawn), it is also effective to heat theshape memory alloy member by means of the change in environmentaltemperature, an external heater and the like. In contrast, in aconfiguration that indirectly heats the shape memory alloy member bymeans of heat transfer by heating a member around which the shape memoryalloy member is wound (for example, a configuration disclosed inJapanese Laid-Open Patent Publication No. HEI 5-224136), it is notpossible to obtain a sufficient amount of displacement.

Besides the reduction of the contacting part between the shape memoryalloy member and the bending member, it is also possible to suppress thedecrease in the amount of displacement of the shape memory alloy memberby using a material having a low coefficient of thermal conductivity asthe bending member (or the contact portion contacting the shape memoryalloy member).

Moreover, in the above described Embodiments 1 through 21, although atension coil spring is used as a resilient member for urging the shapememory alloy member, the resilient member is not limited to this. It isalso possible to use a compressive coil spring, a torsion coil spring, aplate spring, a rubber or the like. Furthermore, the resilient member isnot limited to a conductive material such as metal. If a material otherthan the conductive material is used as the resilient member, and if theshape memory alloy member is heated by energizing, it is only necessaryto energize between both ends of the shape memory alloy member.Furthermore, instead of using the resilient member, it is possible toemploy various methods for urging the shape memory alloy member, forexample, urging the movable body by means of gravity.

1. A driving device comprising: a bendable shape memory alloy member; anurging means which applies a tension to said shape memory alloy memberin a longitudinal direction thereof; and a bending means which bendssaid shape memory alloy member, said bending means having a plurality ofcontact portions contacting said shape memory alloy member, saidplurality of contact portions being disposed along a closed path,wherein said contact portions contact said shape memory alloy member sothat a tension is applied to said shape memory alloy member in alongitudinal direction thereof.
 2. The driving device according to claim1, wherein said bending means has a bending member having a plurality ofconvex portions on a circumferential surface thereof, and said aplurality of convex portions constitute said plurality of contactportions.
 3. The driving device according to claim 1, wherein saidbending means is rotatable.
 4. The driving device according to claim 1,wherein said bending means has a protrusion that further protrudes fromsaid contact portion, and said shape memory alloy member is further bentby said projection.
 5. The driving device according to claim 1, whereinsaid contact portions are constituted by a plurality of pin-shapedmembers disposed along a closed path.
 6. A driving device comprising: abendable shape memory alloy member; an urging means which applies atension to said shape memory alloy member in a longitudinal directionthereof; and a bending means which bends said shape memory alloy member,said bending means having a structural body and a plurality ofprojections formed on said structural body, wherein said projectionscontact said shape memory alloy member so that a tension is applied tosaid shape memory alloy member in a longitudinal direction thereof. 7.The driving device according to claim 6, wherein said projections have aplurality of convex portions on circumferential surfaces thereof, and aplurality of convex portions contact said shape memory alloy member. 8.The driving device according to claim 6, wherein said bending meansfurther has a protrusion that protrudes from said structural body, andsaid shape memory alloy member is bent by contacting said protrusion. 9.A driving device comprising: a bendable shape memory alloy member; anurging means which applies a tension to said shape memory alloy memberin a longitudinal direction thereof; a bending means which bends saidshape memory alloy member, said bending means having a plurality ofcontact portions contacting said shape memory alloy member; and anenergizing circuit for causing a current to flow through said shapememory alloy member, wherein said contact portions contact said shapememory alloy member so that a tension is applied to said shape memoryalloy member in the longitudinal direction thereof, and said energizingcircuit causes a current to flow through said shape memory alloy membervia said contact portions.
 10. The driving device according to claim 9,wherein said energizing circuit causes the current to flow through saidshape memory alloy member via two contact portions, among said pluralityof contact portions, respectively closest to both ends of said shapememory alloy member.
 11. The driving device according to claim 9,wherein said energizing circuit causes a current to flow through saidshape memory alloy member via two contact portions adjacent to eachother, among said plurality of contact portions.
 12. The driving deviceaccording to claim 9, wherein a current caused to flow through saidshape memory alloy member by said energizing circuit via said contactportions differs according to a position in a longitudinal direction ofsaid shape memory alloy member.
 13. The driving device according toclaim 9, wherein said contact portions are pin-shaped members.
 14. Thedriving device according to claim 9, wherein said plurality of contactportions are conductive portions formed on a surface of a structuralbody made of insulation material.